diff --git a/README.md b/README.md
index 4ed8232..ee6f87f 100644
--- a/README.md
+++ b/README.md
@@ -96,12 +96,12 @@ with npm (recommended):
 
     <script>
         // create the editor
-        var container = document.getElementById("jsoneditor")
-        var options = {}
-        var editor = new JSONEditor(container, options)
+        const container = document.getElementById("jsoneditor")
+        const options = {}
+        const editor = new JSONEditor(container, options)
 
         // set json
-        var json = {
+        const initialJson = {
             "Array": [1, 2, 3],
             "Boolean": true,
             "Null": null,
@@ -109,10 +109,10 @@ with npm (recommended):
             "Object": {"a": "b", "c": "d"},
             "String": "Hello World"
         }
-        editor.set(json)
+        editor.set(initialJson)
 
         // get json
-        var json = editor.get()
+        const updatedJson = editor.get()
     </script>
 </body>
 </html>
diff --git a/examples/01_basic_usage.html b/examples/01_basic_usage.html
index f8d76f2..875bd29 100644
--- a/examples/01_basic_usage.html
+++ b/examples/01_basic_usage.html
@@ -22,13 +22,13 @@
 
 <script>
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var options = {};
-  var editor = new JSONEditor(container, options);
+  const container = document.getElementById('jsoneditor')
+  const options = {}
+  const editor = new JSONEditor(container, options)
 
   // set json
   document.getElementById('setJSON').onclick = function () {
-    var json = {
+    const json = {
       'array': [1, 2, 3],
       'boolean': true,
       'color': '#82b92c',
@@ -36,15 +36,15 @@
       'number': 123,
       'object': {'a': 'b', 'c': 'd'},
       'string': 'Hello World'
-    };
-    editor.set(json);
-  };
+    }
+    editor.set(json)
+  }
 
   // get json
   document.getElementById('getJSON').onclick = function () {
-    var json = editor.get();
-    alert(JSON.stringify(json, null, 2));
-  };
+    const json = editor.get()
+    alert(JSON.stringify(json, null, 2))
+  }
 </script>
 </body>
 </html>
diff --git a/examples/02_viewer.html b/examples/02_viewer.html
index f6d9532..0404ffb 100644
--- a/examples/02_viewer.html
+++ b/examples/02_viewer.html
@@ -23,22 +23,22 @@
 <div id="jsoneditor"></div>
 
 <script>
-  var container = document.getElementById('jsoneditor');
+  const container = document.getElementById('jsoneditor')
 
-  var options = {
+  const options = {
     mode: 'view'
-  };
+  }
 
-  var json = {
+  const json = {
     'array': [1, 2, 3],
     'boolean': true,
     'null': null,
     'number': 123,
     'object': {'a': 'b', 'c': 'd'},
     'string': 'Hello World'
-  };
+  }
 
-  var editor = new JSONEditor(container, options, json);
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/03_switch_mode.html b/examples/03_switch_mode.html
index 26218a9..b729639 100644
--- a/examples/03_switch_mode.html
+++ b/examples/03_switch_mode.html
@@ -38,29 +38,29 @@
 <div id="jsoneditor"></div>
 
 <script>
-  var container = document.getElementById('jsoneditor');
+  const container = document.getElementById('jsoneditor')
 
-  var options = {
+  const options = {
     mode: 'tree',
     modes: ['code', 'form', 'text', 'tree', 'view', 'preview'], // allowed modes
     onError: function (err) {
-      alert(err.toString());
+      alert(err.toString())
     },
     onModeChange: function (newMode, oldMode) {
-      console.log('Mode switched from', oldMode, 'to', newMode);
+      console.log('Mode switched from', oldMode, 'to', newMode)
     }
-  };
+  }
 
-  var json = {
+  const json = {
     "array": [1, 2, 3],
     "boolean": true,
     "null": null,
     "number": 123,
     "object": {"a": "b", "c": "d"},
     "string": "Hello World"
-  };
+  }
 
-  var editor = new JSONEditor(container, options, json);
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/04_load_and_save.html b/examples/04_load_and_save.html
index d8be3c9..4a2b68a 100644
--- a/examples/04_load_and_save.html
+++ b/examples/04_load_and_save.html
@@ -38,36 +38,36 @@
 
 <script>
   // create the editor
-  var editor = new JSONEditor(document.getElementById('jsoneditor'));
+  const editor = new JSONEditor(document.getElementById('jsoneditor'))
 
   // Load a JSON document
   FileReaderJS.setupInput(document.getElementById('loadDocument'), {
     readAsDefault: 'Text',
     on: {
       load: function (event, file) {
-        editor.setText(event.target.result);
+        editor.setText(event.target.result)
       }
     }
-  });
+  })
 
   // Save a JSON document
   document.getElementById('saveDocument').onclick = function () {
     // Save Dialog
-    fname = window.prompt("Save as...");
-    
+    let fname = window.prompt("Save as...")
+
     // Check json extension in file name
-    if(fname.indexOf(".")==-1){
-      fname = fname + ".json";
-    }else{
-      if(fname.split('.').pop().toLowerCase() == "json"){
+    if (fname.indexOf(".") === -1) {
+      fname = fname + ".json"
+    } else {
+      if (fname.split('.').pop().toLowerCase() === "json") {
         // Nothing to do
-      }else{
-        fname = fname.split('.')[0] + ".json";
+      } else {
+        fname = fname.split('.')[0] + ".json"
       }
-    } 
-    var blob = new Blob([editor.getText()], {type: 'application/json;charset=utf-8'});
-    saveAs(blob, fname);
-  };
+    }
+    const blob = new Blob([editor.getText()], {type: 'application/json;charset=utf-8'})
+    saveAs(blob, fname)
+  }
 </script>
 </body>
 </html>
diff --git a/examples/05_custom_fields_editable.html b/examples/05_custom_fields_editable.html
index d8a5dae..67483cc 100644
--- a/examples/05_custom_fields_editable.html
+++ b/examples/05_custom_fields_editable.html
@@ -25,9 +25,9 @@
   <div id="jsoneditor"></div>
 
   <script>
-    var container = document.getElementById('jsoneditor');
+    const container = document.getElementById('jsoneditor')
 
-    var options = {
+    const options = {
       onEditable: function (node) {
         // node is an object like:
         //   {
@@ -37,27 +37,27 @@
         //   }
         switch (node.field) {
           case '_id':
-            return false;
+            return false
 
           case 'name':
             return {
               field: false,
               value: true
-            };
+            }
 
           default:
-            return true;
+            return true
         }
       }
-    };
+    }
 
-    var json = {
+    const json = {
       _id: 123456,
       name: 'John',
       age: 32
-    };
+    }
 
-    var editor = new JSONEditor(container, options, json);
+    const editor = new JSONEditor(container, options, json)
   </script>
 </body>
 </html>
diff --git a/examples/06_custom_styling.html b/examples/06_custom_styling.html
index 37d9add..e185486 100644
--- a/examples/06_custom_styling.html
+++ b/examples/06_custom_styling.html
@@ -22,30 +22,30 @@
 
 </head>
 <body>
-    <p>
-        This example demonstrates how to customize the look of JSONEditor,
-        the editor below has a dark theme. Note that the example isn't worked
-        out for the mode <code>code</code>. To do that, you can load and configure
-        a custom theme for the Ace editor.
-    </p>
+<p>
+    This example demonstrates how to customize the look of JSONEditor,
+    the editor below has a dark theme. Note that the example isn't worked
+    out for the mode <code>code</code>. To do that, you can load and configure
+    a custom theme for the Ace editor.
+</p>
 
-    <div id="jsoneditor"></div>
+<div id="jsoneditor"></div>
 
-    <script>
+<script>
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var options = {
+  const container = document.getElementById('jsoneditor')
+  const options = {
     modes: ['text', 'tree']
-  };
-  var json = {
+  }
+  const json = {
     'array': [1, 2, 3],
     'boolean': true,
     'null': null,
     'number': 123,
     'object': {'a': 'b', 'c': 'd'},
     'string': 'Hello World'
-  };
-  var editor = new JSONEditor(container, options, json);
-    </script>
+  }
+  const editor = new JSONEditor(container, options, json)
+</script>
 </body>
 </html>
diff --git a/examples/07_json_schema_validation.html b/examples/07_json_schema_validation.html
index b3bc8d5..087cf37 100644
--- a/examples/07_json_schema_validation.html
+++ b/examples/07_json_schema_validation.html
@@ -34,7 +34,7 @@
 <div id="jsoneditor"></div>
 
 <script>
-  var schema = {
+  const schema = {
     "title": "Employee",
     "description": "Object containing employee details",
     "type": "object",
@@ -74,9 +74,9 @@
       }
     },
     "required": ["firstName", "lastName"]
-  };
+  }
 
-  var job = {
+  const job = {
     "title": "Job description",
     "type": "object",
     "required": ["address"],
@@ -106,9 +106,9 @@
         "examples": [100, 110, 120]
       }
     }
-  };
+  }
 
-  var json = {
+  const json = {
     firstName: 'John',
     lastName: 'Doe',
     gender: null,
@@ -119,18 +119,18 @@
       role: 'developer',
       salary: 100
     }
-  };
+  }
 
-  var options = {
+  const options = {
     schema: schema,
     schemaRefs: {"job": job},
     mode: 'tree',
     modes: ['code', 'text', 'tree', 'preview']
-  };
+  }
 
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var editor = new JSONEditor(container, options, json);
+  const container = document.getElementById('jsoneditor')
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/08_custom_ace.html b/examples/08_custom_ace.html
index fe0b4fd..077c51b 100644
--- a/examples/08_custom_ace.html
+++ b/examples/08_custom_ace.html
@@ -52,21 +52,21 @@
 
 <script>
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var options = {
+  const container = document.getElementById('jsoneditor')
+  const options = {
     modes: ['text', 'code', 'tree', 'form', 'view'],
     mode: 'code',
     ace: ace
-  };
-  var json = {
+  }
+  const json = {
     'array': [1, 2, 3],
     'boolean': true,
     'null': null,
     'number': 123,
     'object': {'a': 'b', 'c': 'd'},
     'string': 'Hello World'
-  };
-  var editor = new JSONEditor(container, options, json);
+  }
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/09_readonly_text_mode.html b/examples/09_readonly_text_mode.html
index 05cb4f8..a9b18c7 100644
--- a/examples/09_readonly_text_mode.html
+++ b/examples/09_readonly_text_mode.html
@@ -38,9 +38,9 @@
 <div id="jsoneditor"></div>
 
 <script>
-  var container = document.getElementById('jsoneditor');
+  const container = document.getElementById('jsoneditor')
 
-  var options = {
+  const options = {
     mode: 'text',
     modes: ['text', 'code'],
     onEditable: function (node) {
@@ -51,23 +51,23 @@
       }
     },
     onError: function (err) {
-      alert(err.toString());
+      alert(err.toString())
     },
     onModeChange: function (newMode, oldMode) {
-      console.log('Mode switched from', oldMode, 'to', newMode);
+      console.log('Mode switched from', oldMode, 'to', newMode)
     }
-  };
+  }
 
-  var json = {
+  const json = {
     "array": [1, 2, 3],
     "boolean": true,
     "null": null,
     "number": 123,
     "object": {"a": "b", "c": "d"},
     "string": "Hello World"
-  };
+  }
 
-  var editor = new JSONEditor(container, options, json);
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/10_templates.html b/examples/10_templates.html
index 742bdef..e47c815 100644
--- a/examples/10_templates.html
+++ b/examples/10_templates.html
@@ -27,46 +27,45 @@
 <div id="jsoneditor"></div>
 
 <script>
-
-  var json = [
+  const json = [
     {
       firstName: 'John',
       lastName: 'Doe',
       age: 28
     }
-  ];
+  ]
 
-  var options = {
-      templates: [
-          {
-              text: 'Person',
-              title: 'Insert a Person Node',
-              className: 'jsoneditor-type-object',
-              field: 'PersonTemplate',
-              value: {
-                  'firstName': 'John',
-                  'lastName': 'Do',
-                  'age': 28
-              }
-          },
-          {
-              text: 'Address',
-              title: 'Insert a Address Node',
-              field: 'AddressTemplate',
-              value: {
-                  'street': '',
-                  'city': '',
-                  'state': '',
-                  'ZIP code': ''
-              }
-          }
-      ]
-  };
+  const options = {
+    templates: [
+      {
+        text: 'Person',
+        title: 'Insert a Person Node',
+        className: 'jsoneditor-type-object',
+        field: 'PersonTemplate',
+        value: {
+          'firstName': 'John',
+          'lastName': 'Do',
+          'age': 28
+        }
+      },
+      {
+        text: 'Address',
+        title: 'Insert a Address Node',
+        field: 'AddressTemplate',
+        value: {
+          'street': '',
+          'city': '',
+          'state': '',
+          'ZIP code': ''
+        }
+      }
+    ]
+  }
 
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var editor = new JSONEditor(container, options, json);
-  editor.expandAll();
+  const container = document.getElementById('jsoneditor')
+  const editor = new JSONEditor(container, options, json)
+  editor.expandAll()
 </script>
 </body>
 </html>
diff --git a/examples/11_autocomplete_basic.html b/examples/11_autocomplete_basic.html
index df42354..b17a60d 100644
--- a/examples/11_autocomplete_basic.html
+++ b/examples/11_autocomplete_basic.html
@@ -2,11 +2,10 @@
 <html>
 <head>
   <title>JSONEditor | Auto Complete</title>
-    
+
   <link href="../dist/jsoneditor.css" rel="stylesheet" type="text/css">
   <script src="../dist/jsoneditor.js"></script>
 
-
   <style type="text/css">
     #jsoneditor {
       width: 500px;
@@ -22,30 +21,30 @@
 </head>
 <body>
 <p>
-    This example demonstrates how to autocomplete works, options available are: 'apple','cranberry','raspberry','pie', 'mango', 'mandarine', 'melon', 'appleton'.
+  This example demonstrates how to autocomplete works, options available are: 'apple','cranberry','raspberry','pie', 'mango', 'mandarine', 'melon', 'appleton'.
 </p>
 
 <div id="jsoneditor"></div>
 
 <script>
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var options = {
+  const container = document.getElementById('jsoneditor')
+  const options = {
     autocomplete: {
       getOptions: function () {
         return ['apple', 'cranberry', 'raspberry', 'pie', 'mango', 'mandarine', 'melon', 'appleton'];
       }
     }
-  };
-  var json = {
+  }
+  const json = {
     'array': [{'field1':'v1', 'field2':'v2'}, 2, 3],
     'boolean': true,
     'null': null,
     'number': 123,
     'object': {'a': 'b', 'c': 'd'},
     'string': 'Hello World'
-  };
-  var editor = new JSONEditor(container, options, json);
+  }
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/12_autocomplete_dynamic.html b/examples/12_autocomplete_dynamic.html
index e6c008f..d4da92c 100644
--- a/examples/12_autocomplete_dynamic.html
+++ b/examples/12_autocomplete_dynamic.html
@@ -7,7 +7,6 @@
   <script src="../dist/jsoneditor.js"></script>
   <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>
 
-
   <style type="text/css">
     #jsoneditor {
       width: 500px;
@@ -30,39 +29,39 @@
 
 <script>
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var options = {
+  const container = document.getElementById('jsoneditor')
+  const options = {
     autocomplete: {
       applyTo:['value'],
       filter: 'contain',
       trigger: 'focus',
       getOptions: function (text, path, input, editor) {
         return new Promise(function (resolve, reject) {
-          var options = extractUniqueWords(editor.get());
-          if (options.length > 0) resolve(options); else reject();
-        });
+          const options = extractUniqueWords(editor.get())
+          if (options.length > 0) resolve(options) else reject()
+        })
       }
     }
-  };
+  }
 
   // helper function to extract all unique words in the keys and values of a JSON object
   function extractUniqueWords (json) {
     return _.uniq(_.flatMapDeep(json, function (value, key) {
       return _.isObject(value)
-          ? [key]
-          : [key, String(value)]
+              ? [key]
+              : [key, String(value)]
     }))
   }
 
-  var json = {
+  const json = {
     'array': [{'field1':'v1', 'field2':'v2'}, 2, 3],
     'boolean': true,
     'null': null,
     'number': 123,
     'object': {'a': 'b', 'c': 'd'},
     'string': 'Hello World'
-  };
-  var editor = new JSONEditor(container, options, json);
+  }
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/13_autocomplete_advanced.html b/examples/13_autocomplete_advanced.html
index 183c16d..1f2f913 100644
--- a/examples/13_autocomplete_advanced.html
+++ b/examples/13_autocomplete_advanced.html
@@ -31,74 +31,78 @@
 
 <script>
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var activationChar = '*';
-  var options = {
+  const container = document.getElementById('jsoneditor')
+  const activationChar = '*'
+  const options = {
     autocomplete: {
       confirmKeys: [39, 35, 9, 190], // Confirm Autocomplete Keys: [right, end, tab, '.']  // By default are only [right, end, tab]
       caseSensitive: false,
 
       getOptions: function (text, path, input, editor) {
-        if (!text.startsWith(activationChar) || input !== 'value') return [];
-        var data = {};
-        var startFrom = 0;
-        var lastPoint = text.lastIndexOf('.');
-        var jsonObj = editor.get();
+        if (!text.startsWith(activationChar) || input !== 'value') return []
+        let data = {}
+        let startFrom = 0
+        const lastPoint = text.lastIndexOf('.')
+        const jsonObj = editor.get()
         if ((lastPoint > 0) && (text.length > 1)) {
-            data = jsonpath.query(jsonObj, '$.' + text.substring(activationChar.length, lastPoint));
-            if (data.length > 0) data = data[0]; else data = {};
-            // Indicate that autocompletion should start after the . (ignoring the first part)
-            startFrom = text.lastIndexOf('.') + 1;
+          data = jsonpath.query(jsonObj, '$.' + text.substring(activationChar.length, lastPoint))
+          if (data.length > 0) {
+            data = data[0]
+          } else {
+            data = {}
+          }
+          // Indicate that autocompletion should start after the . (ignoring the first part)
+          startFrom = text.lastIndexOf('.') + 1
+        } else {
+          data = jsonObj
         }
-        else
-            data = jsonObj;
 
-        var optionsStr = YaskON.stringify(data, null, activationChar);
-        var options = optionsStr.split('\n');
-        return { startFrom: startFrom, options: options };
+        const optionsStr = YaskON.stringify(data, null, activationChar)
+        const options = optionsStr.split('\n')
+        return { startFrom: startFrom, options: options }
       }
     }
-  };
+  }
 
   // helper function to auto complete paths of a JSON object
-  var YaskON = {
+  const YaskON = {
     // Return first level json paths by the node 'o'
     stringify: function (o, prefix, activationChar) {
-      prefix = prefix || '';
+      prefix = prefix || ''
       switch (typeof o) {
         case 'object':
-          var output = '';
+          let output = ''
           if (Array.isArray(o)) {
             o.forEach(function (e, index) {
-              output += activationChar + prefix + '[' + index + ']' + '\n';
-            }.bind(this));
-            return output;
+              output += activationChar + prefix + '[' + index + ']' + '\n'
+            }.bind(this))
+            return output
           }
-          output = '';
-          for (var k in o) {
+          output = ''
+          for (let k in o) {
             if (o.hasOwnProperty(k)) {
-              if (prefix === '') output += this.stringify(o[k], k, activationChar);
+              if (prefix === '') output += this.stringify(o[k], k, activationChar)
             }
           }
           if (prefix !== '') output += activationChar + prefix + '\n'
-          return output;
+          return output
         case 'function':
-          return '';
+          return ''
         default:
-          return prefix + '\n';
+          return prefix + '\n'
       }
     }
-  };
+  }
 
-  var json = {
+  const json = {
     'array': [{ 'field1': 'v1', 'field2': 'v2' }, 2, 3],
     'boolean': true,
     'null': null,
     'number': 123,
     'object': { 'a': 'b', 'c': 'd' },
     'string': 'Hello World'
-  };
-  var editor = new JSONEditor(container, options, json);
+  }
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/14_translate.html b/examples/14_translate.html
index 2529047..d545e08 100644
--- a/examples/14_translate.html
+++ b/examples/14_translate.html
@@ -16,42 +16,42 @@
 </head>
 
 <body>
-  <p>
-    JSONEditor has support for multiple languages (i18n), in this case uses <code>pt-BR</code>.
-  </p>
-  <div id="jsoneditor"></div>
+<p>
+  JSONEditor has support for multiple languages (i18n), in this case uses <code>pt-BR</code>.
+</p>
+<div id="jsoneditor"></div>
 
-  <script>
-    // create the editor
-    var container = document.getElementById('jsoneditor');
-    var options = {
-      // switch between pt-BR or en for testing forcing a language
-      // leave blank to get language
-      'language': 'pt-BR',
-      'languages': {
-        'pt-BR': {
-          'auto': 'Automático testing'
-        },
-        'en': {
-          'auto': 'Auto testing'
-        },
-        'newlang': {
-          'auto': 'Auto new lang'
-        }
+<script>
+  // create the editor
+  const container = document.getElementById('jsoneditor')
+  const options = {
+    // switch between pt-BR or en for testing forcing a language
+    // leave blank to get language
+    'language': 'pt-BR',
+    'languages': {
+      'pt-BR': {
+        'auto': 'Automático testing'
+      },
+      'en': {
+        'auto': 'Auto testing'
+      },
+      'newlang': {
+        'auto': 'Auto new lang'
       }
-    };
-    var editor = new JSONEditor(container, options);
+    }
+  }
+  const editor = new JSONEditor(container, options)
 
-    var json = {
-      'array': [1, 2, 3],
-      'boolean': true,
-      'null': null,
-      'number': 123,
-      'object': { 'a': 'b', 'c': 'd' },
-      'string': 'Hello World'
-    };
-    editor.set(json);
-  </script>
+  const json = {
+    'array': [1, 2, 3],
+    'boolean': true,
+    'null': null,
+    'number': 123,
+    'object': { 'a': 'b', 'c': 'd' },
+    'string': 'Hello World'
+  }
+  editor.set(json)
+</script>
 </body>
 
 </html>
\ No newline at end of file
diff --git a/examples/15_selection_api.html b/examples/15_selection_api.html
index 3785789..f3c9ba7 100644
--- a/examples/15_selection_api.html
+++ b/examples/15_selection_api.html
@@ -58,52 +58,50 @@
 </form>
 
 <script>
-  var container, options, json, editor;
+  const container = document.getElementById('jsoneditor')
 
-  container = document.getElementById('jsoneditor');
-
-  options = {
+  const options = {
     mode: 'tree',
     modes: ['code', 'form', 'text', 'tree', 'view', 'preview'], // allowed modes
     onError: function (err) {
-      alert(err.toString());
+      alert(err.toString())
     },
     onChange: function () {
-      console.log('change');
+      console.log('change')
     },
     onModeChange: function (mode) {
-      var treeMode = document.getElementById('treeModeSelection');
-      var textMode = document.getElementById('textModeSelection');
+      const treeMode = document.getElementById('treeModeSelection')
+      const textMode = document.getElementById('textModeSelection')
 
-      treeMode.style.display = textMode.style.display = 'none';
+      treeMode.style.display = textMode.style.display = 'none'
 
       if (mode === 'code' || mode === 'text') {
-        textMode.style.display = 'inline';
+        textMode.style.display = 'inline'
       } else {
-        treeMode.style.display = 'inline';
+        treeMode.style.display = 'inline'
       }
     },
     indentation: 4,
     escapeUnicode: true,
     onTextSelectionChange: function(start, end, text) {
-      var rangeEl = document.getElementById('textRange');
-      rangeEl.innerHTML = 'start: ' + JSON.stringify(start) + ', end: ' + JSON.stringify(end);
-      var textEl = document.getElementById('selectedText');
-      textEl.innerHTML = text;
+      const rangeEl = document.getElementById('textRange')
+      rangeEl.innerHTML = 'start: ' + JSON.stringify(start) + ', end: ' + JSON.stringify(end)
+      const textEl = document.getElementById('selectedText')
+      textEl.innerHTML = text
     },
     onSelectionChange: function(start, end) {
-      var nodesEl = document.getElementById('selectedNodes');
-      nodesEl.innerHTML = '';
+      const nodesEl = document.getElementById('selectedNodes')
+      nodesEl.innerHTML = ''
       if (start) {
-        nodesEl.innerHTML = ('start: '  + JSON.stringify(start));
+        nodesEl.innerHTML = ('start: '  + JSON.stringify(start))
         if (end) {
-          nodesEl.innerHTML += ('<br/>end: '  + JSON.stringify(end));
+          nodesEl.innerHTML += ('<br/>end: '  + JSON.stringify(end))
         }
       }
     }
-  };
+  }
 
-  json = {
+  const json = {
     "array": [1, 2, [3,4,5]],
     "boolean": true,
     "htmlcode": '&quot;',
@@ -115,12 +113,12 @@
     "object": {"a": "b", "c": "d"},
     "string": "Hello World",
     "url": "http://jsoneditoronline.org"
-  };
+  }
 
-  window.editor = new JSONEditor(container, options, json);
+  window.editor = new JSONEditor(container, options, json)
 
-  console.log('json', json);
-  console.log('string', JSON.stringify(json));
+  console.log('json', json)
+  console.log('string', JSON.stringify(json))
 </script>
 </body>
 </html>
diff --git a/examples/16_synchronize_editors.html b/examples/16_synchronize_editors.html
index 58d275c..ccdb5da 100644
--- a/examples/16_synchronize_editors.html
+++ b/examples/16_synchronize_editors.html
@@ -35,30 +35,30 @@
 
 <script>
   // create editor 1
-  var editor1 = new JSONEditor(document.getElementById('jsoneditor1'), {
+  const  editor1 = new JSONEditor(document.getElementById('jsoneditor1'), {
     onChangeText: function (jsonString) {
-      editor2.updateText(jsonString);
+      editor2.updateText(jsonString)
     }
-  });
+  })
 
   // create editor 2
-  var editor2 = new JSONEditor(document.getElementById('jsoneditor2'), {
+  const  editor2 = new JSONEditor(document.getElementById('jsoneditor2'), {
     onChangeText: function (jsonString) {
-      editor1.updateText(jsonString);
+      editor1.updateText(jsonString)
     }
-  });
+  })
 
   // set initial data in both editors
-  var json = {
+  const  json = {
     'array': [1, 2, 3],
     'boolean': true,
     'null': null,
     'number': 123,
     'object': {'a': 'b', 'c': 'd'},
     'string': 'Hello World'
-  };
-  editor1.set(json);
-  editor2.set(json);
+  }
+  editor1.set(json)
+  editor2.set(json)
 </script>
 </body>
 </html>
diff --git a/examples/17_on_event_api.html b/examples/17_on_event_api.html
index 59fd65b..0da1426 100644
--- a/examples/17_on_event_api.html
+++ b/examples/17_on_event_api.html
@@ -37,42 +37,42 @@
 </form>
 
 <script>
-  var container, options, json;
+  const container = document.getElementById('jsoneditor')
 
-  container = document.getElementById('jsoneditor');
-
-  options = {
+  const options = {
     mode: 'tree',
     modes: ['code', 'form', 'text', 'tree', 'view', 'preview'], // allowed modes
     name: "jsonContent",
     onError: function (err) {
-      alert(err.toString());
+      alert(err.toString())
     },
     onEvent: function(node, event) {
       if (event.type === 'click') {
-        var message = 'click on <' + node.field +
+        let message = 'click on <' + node.field +
           '> under path <' + node.path + 
-          '> with pretty path: <' + prettyPrintPath(node.path) + '>';
-        if (node.value) message += ' with value <' + node.value + '>';
-        console.log(message);
+          '> with pretty path: <' + prettyPrintPath(node.path) + '>'
+        if (node.value) {
+          message += ' with value <' + node.value + '>'
+        }
+        console.log(message)
       }
       function prettyPrintPath(path) {
-        var str = '';
-        for (var i=0; i<path.length; i++) {
-          var element = path[i];
+        let str = ''
+        for (let i=0; i<path.length; i++) {
+          const element = path[i]
           if (typeof element === 'number') {
             str += '[' + element + ']'
           } else {
-            if (str.length > 0) str += ',';
-            str += element; 
+            if (str.length > 0) str += ','
+            str += element
           }
         }
-        return str;
+        return str
       }
     }
-  };
+  }
 
-  json = {
+  const json = {
     "array": [1, 2, [3,4,5]],
     "boolean": true,
     "htmlcode": '&quot;',
@@ -85,12 +85,12 @@
     "string": "Hello World",
     "url": "http://jsoneditoronline.org",
     "[0]": "zero"
-  };
+  }
   
-  window.editor = new JSONEditor(container, options, json);
+  window.editor = new JSONEditor(container, options, json)
 
-  console.log('json', json);
-  console.log('string', JSON.stringify(json));
+  console.log('json', json)
+  console.log('string', JSON.stringify(json))
 </script>
 </body>
 </html>
diff --git a/examples/18_custom_validation.html b/examples/18_custom_validation.html
index 37e496c..0a9b18d 100644
--- a/examples/18_custom_validation.html
+++ b/examples/18_custom_validation.html
@@ -28,7 +28,7 @@
 <div id="jsoneditor"></div>
 
 <script>
-  var json = {
+  const json = {
     team: [
       {
         name: 'Joe',
@@ -42,9 +42,9 @@
         name: 'Jack'
       }
     ]
-  };
+  }
 
-  var options = {
+  const options = {
     mode: 'tree',
     modes: ['code', 'text', 'tree', 'preview'],
     onValidate: function (json) {
@@ -52,59 +52,56 @@
       // - team, names, and ages must be filled in and be of correct type
       // - a team must have 4 members
       // - at lease one member of the team must be adult
-      var errors = [];
+      const errors = []
 
       if (json && Array.isArray(json.team)) {
         // check whether each team member has name and age filled in correctly
         json.team.forEach(function (member, index) {
           if (typeof member !== 'object') {
-            errors.push({ path: ['team', index], message: 'Member must be an object with properties "name" and "age"' })
+            errors.push({path: ['team', index], message: 'Member must be an object with properties "name" and "age"'})
           }
 
           if ('name' in member) {
             if (typeof member.name !== 'string') {
-              errors.push({ path: ['team', index, 'name'], message: 'Name must be a string' })
+              errors.push({path: ['team', index, 'name'], message: 'Name must be a string'})
             }
-          }
-          else {
-            errors.push({ path: ['team', index], message: 'Required property "name"" missing' })
+          } else {
+            errors.push({path: ['team', index], message: 'Required property "name"" missing'})
           }
 
           if ('age' in member) {
             if (typeof member.age !== 'number') {
-              errors.push({ path: ['team', index, 'age'], message: 'Age must be a number' })
+              errors.push({path: ['team', index, 'age'], message: 'Age must be a number'})
             }
+          } else {
+            errors.push({path: ['team', index], message: 'Required property "age" missing'})
           }
-          else {
-            errors.push({ path: ['team', index], message: 'Required property "age" missing' })
-          }
-        });
+        })
 
         // check whether the team consists of exactly four members
         if (json.team.length !== 4) {
-          errors.push({ path: ['team'], message: 'A team must have 4 members' })
+          errors.push({path: ['team'], message: 'A team must have 4 members'})
         }
 
         // check whether there is at least one adult member in the team
-        var adults = json.team.filter(function (member) {
-          return member ? member.age >= 18 : false;
-        });
+        const adults = json.team.filter(function (member) {
+          return member ? member.age >= 18 : false
+        })
         if (adults.length === 0) {
-          errors.push({ path: ['team'], message: 'A team must have at least one adult person (age >= 18)' })
+          errors.push({path: ['team'], message: 'A team must have at least one adult person (age >= 18)'})
         }
-      }
-      else {
-        errors.push({ path: [], message: 'Required property "team" missing or not an Array' })
+      } else {
+        errors.push({path: [], message: 'Required property "team" missing or not an Array'})
       }
 
-      return errors;
+      return errors
     }
-  };
+  }
 
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var editor = new JSONEditor(container, options, json);
-  editor.expandAll();
+  const container = document.getElementById('jsoneditor')
+  const editor = new JSONEditor(container, options, json)
+  editor.expandAll()
 </script>
 </body>
 </html>
diff --git a/examples/19_custom_validation_async.html b/examples/19_custom_validation_async.html
index 2fe82fb..68b2d34 100644
--- a/examples/19_custom_validation_async.html
+++ b/examples/19_custom_validation_async.html
@@ -29,15 +29,15 @@
 <div id="jsoneditor"></div>
 
 <script>
-  var json = {
+  const json = {
     customers: [
       {name: 'Joe'},
       {name: 'Sarah'},
       {name: 'Harry'},
     ]
-  };
+  }
 
-  var options = {
+  const options = {
     mode: 'tree',
     modes: ['code', 'text', 'tree', 'preview'],
     onValidate: function (json) {
@@ -54,35 +54,35 @@
                   }
                 }
                 else {
-                  return null;
+                  return null
                 }
-              });
+              })
             }))
             .then(function (errors) {
               return errors.filter(function (error) {
-                return error != null;
+                return error != null
               })
-            });
+            })
       }
       else {
-        return null;
+        return null
       }
     }
-  };
+  }
 
   // create the editor
-  var container = document.getElementById('jsoneditor');
-  var editor = new JSONEditor(container, options, json);
-  editor.expandAll();
+  const container = document.getElementById('jsoneditor')
+  const editor = new JSONEditor(container, options, json)
+  editor.expandAll()
 
   // this function fakes a request (asynchronous) to a server to validate the existence of a customer
   function isExistingCustomer (customerName) {
     return new Promise(function (resolve, reject) {
       setTimeout(function () {
-        var customers = ['Joe', 'Harry', 'Megan'];
-        var exists = customers.indexOf(customerName) !== -1;
-        resolve(exists);
-      }, 500);
+        const customers = ['Joe', 'Harry', 'Megan']
+        const exists = customers.indexOf(customerName) !== -1
+        resolve(exists)
+      }, 500)
     })
   }
 </script>
diff --git a/examples/20_custom_css_style_for_nodes.html b/examples/20_custom_css_style_for_nodes.html
index 23e4606..7732809 100644
--- a/examples/20_custom_css_style_for_nodes.html
+++ b/examples/20_custom_css_style_for_nodes.html
@@ -52,66 +52,66 @@
 </div>
 
 <script>
-  var containerLeft = document.getElementById('containerLeft');
-  var containerRight = document.getElementById('containerRight');
+  const containerLeft = document.getElementById('containerLeft')
+  const containerRight = document.getElementById('containerRight')
 
   function findNodeInJson(json, path){
     if(!json || path.length ===0) {
       return {field: undefined, value: undefined}
-    }    
-    var first = path[0];
-    var remainingPath = path.slice(1);
+    }
+    const first = path[0]
+    const remainingPath = path.slice(1)
 
     if(remainingPath.length === 0) {
-      return {field: (typeof json[first] !== 'undefined' ? first : undefined), value: json[first]};
+      return {field: (typeof json[first] !== 'undefined' ? first : undefined), value: json[first]}
     } else {
       return findNodeInJson(json[first], remainingPath)
     }
   }
 
   function onClassName({ path, field, value }) {
-    var thisNode = findNodeInJson(jsonRight, path);
-    var oppositeNode = findNodeInJson(jsonLeft, path);
-    var isValueEqual = JSON.stringify(thisNode.value) === JSON.stringify(oppositeNode.value);
+    const thisNode = findNodeInJson(jsonRight, path)
+    const oppositeNode = findNodeInJson(jsonLeft, path)
+    let isValueEqual = JSON.stringify(thisNode.value) === JSON.stringify(oppositeNode.value)
 
     if(Array.isArray(thisNode.value) && Array.isArray(oppositeNode.value)) {
       isValueEqual = thisNode.value.every(function (e) {
-        return oppositeNode.value.includes(e);
+        return oppositeNode.value.includes(e)
       })
     }
 
     if (thisNode.field === oppositeNode.field && isValueEqual) {
-      return 'the_same_element';
+      return 'the_same_element'
     } else {
       return 'different_element'
     }
   }
 
-  var optionsLeft = {
+  const optionsLeft = {
     mode: 'tree',
     onError: function (err) {
-      alert(err.toString());
+      alert(err.toString())
     },
     onClassName: onClassName,
     onChangeJSON: function (j) {
-      jsonLeft = j;      
+      jsonLeft = j
       window.editorRight.refresh()
     }    
-  };
-  
-  var optionsRight = {
+  }
+
+  const optionsRight = {
     mode: 'tree',
     onError: function (err) {
-      alert(err.toString());
+      alert(err.toString())
     },
     onClassName: onClassName,
     onChangeJSON: function (j) {
-      jsonRight = j;
-      window.editorLeft.refresh();
+      jsonRight = j
+      window.editorLeft.refresh()
     }    
-  };
+  }
 
-  var jsonLeft = {
+  let jsonLeft = {
     "arrayOfArrays": [1, 2, 999, [3,4,5]],
     "someField": true,
     "boolean": true,
@@ -126,9 +126,9 @@
     "string": "Hello World",
     "url": "http://jsoneditoronline.org",
     "[0]": "zero"
-  };
+  }
 
-  var jsonRight = {
+  let jsonRight = {
     "arrayOfArrays": [1, 2, [3,4,5]],
     "boolean": true,
     "htmlcode": '&quot;',
@@ -142,10 +142,10 @@
     "string": "Hello World",
     "url": "http://jsoneditoronline.org",
     "[0]": "zero"
-  };
+  }
   
-  window.editorLeft = new JSONEditor(containerLeft, optionsLeft, jsonLeft);
-  window.editorRight = new JSONEditor(containerRight, optionsRight, jsonRight);
+  window.editorLeft = new JSONEditor(containerLeft, optionsLeft, jsonLeft)
+  window.editorRight = new JSONEditor(containerRight, optionsRight, jsonRight)
 </script>
 </body>
 </html>
diff --git a/examples/21_customize_context_menu.html b/examples/21_customize_context_menu.html
index b894df1..b3553c1 100644
--- a/examples/21_customize_context_menu.html
+++ b/examples/21_customize_context_menu.html
@@ -7,47 +7,44 @@
   <script src="../dist/jsoneditor.js"></script>
 
   <style type="text/css">
-  #jsoneditor {
-    width: 500px;
-    height: 500px;
-  }
+    #jsoneditor {
+      width: 500px;
+      height: 500px;
+    }
 
-  .submenu-highlight { background-color: yellow !important; }
+    .submenu-highlight {
+      background-color: yellow !important;
+    }
 
-  .rainbow {
+    .rainbow {
+      background: linear-gradient(to right, cyan, yellow, violet, green, orange, blue) !important;
+    }
 
-    background: linear-gradient(to right, cyan, yellow, violet, green, orange, blue) !important;
-  }
-
-  .example-class > .jsoneditor-icon {
-
-    background-position: -168px -48px; /* warning triangle */
-
-  }
-
-  .dotty {
-    border-top : 1px dotted #e5e5e5 !important;
-  }
+    .example-class > .jsoneditor-icon {
+      background-position: -168px -48px; /* warning triangle */
+    }
 
+    .dotty {
+      border-top : 1px dotted #e5e5e5 !important;
+    }
   </style>
 </head>
 <body>
-  <h1>Context Menu Customization</h1>
-  <p>
-    This example demonstrates the use of the onCreateMenu callback option, which
-    allows you to customise context menus after they are created but before they
-    are shown to the user. You can alter/delete existing items as well as
-    adding new menu items. See the source code for this example for more
-    information.
-  </p>
-  <div id="jsoneditor"></div>
+<h1>Context Menu Customization</h1>
+<p>
+  This example demonstrates the use of the onCreateMenu callback option, which
+  allows you to customise context menus after they are created but before they
+  are shown to the user. You can alter/delete existing items as well as
+  adding new menu items. See the source code for this example for more
+  information.
+</p>
+<div id="jsoneditor"></div>
 
-  <script>
+<script>
   // create the editor
-  var container = document.getElementById('jsoneditor');
-
-  var options = {
+  const container = document.getElementById('jsoneditor')
 
+  const options = {
     // onCreateMenu allows us to register a call back function to customise
     // the context menu. The callback accpets two parameters, items and path.
     // Items is an array containing the current menu items, and path
@@ -58,11 +55,11 @@
     // Every time the user clicks on a context menu button, the menu
     // is created from scratch and this callback is called.
 
-    onCreateMenu : function (items, node) {
-      var path = node.path
+    onCreateMenu: function (items, node) {
+      const path = node.path
 
       // log the current items and node for inspection
-      console.log('items:', items, 'node:', node);
+      console.log('items:', items, 'node:', node)
 
       // We are going to add a menu item which returns the current node path
       // as a jq path selector ( https://stedolan.github.io/jq/ ). First we
@@ -70,69 +67,49 @@
       // the menu item click property in a moment.
 
       function pathTojq() {
-
-        var pathString = '';
+        let pathString = ''
 
         path.forEach(function (segment, index) { // path is an array, loop through it
-
-          if ( typeof segment == 'number') {  // format the selector for array indexs ...
-
-            pathString += '[' + segment + ']';
-
+          if (typeof segment == 'number') {  // format the selector for array indexs ...
+            pathString += '[' + segment + ']'
           } else {  // ... or object keys
-
-            pathString += '."' + segment + '"';
-
+            pathString += '."' + segment + '"'
           }
-
         })
 
-        alert(pathString); // show it to the user.
-
-      };
+        alert(pathString) // show it to the user.
+      }
 
       // Create a new menu item. For our example, we only want to do this
       // if there is a path (in the case of appendnodes (for new objects)
       // path is null until a node is created)
-
       if (path) {
-
         // Each item in the items array represents a menu item,
         // and requires the following details :
 
-        items.push( {
+        items.push({
+          text: 'jq Path', // the text for the menu item
+          title: 'Show the jq path for this node', // the HTML title attribute
+          className: 'example-class', // the css class name(s) for the menu item
+          click: pathTojq // the function to call when the menu item is clicked
+        })
+      }
 
-          text : 'jq Path', // the text for the menu item
-          title : 'Show the jq path for this node', // the HTML title attribute
-          className : 'example-class', // the css class name(s) for the menu item
-          click : pathTojq // the function to call when the menu item is clicked
-
-        } );
-
-      };
 
       // Now we will iterate through the menu items, which includes the items
       // created by jsoneditor, and the new item we added above. In this
       // example we will just alter the className property for the items, but
       // you can alter any property (e.g. the click callback, text property etc.)
       // for any item, or even delete the whole menu item.
-
       items.forEach(function (item, index, items) {
-
-        if ( "submenu" in item ) {
-
+        if ("submenu" in item) {
           // if the item has a submenu property, it is a submenu heading
           // and contains another array of menu items. Let's colour
           // that yellow...
-
-          items[index].className += ' submenu-highlight';
-
+          items[index].className += ' submenu-highlight'
         } else {
-
           // if it's not a submenu heading, let's make it colorful
-
-          items[index].className += ' rainbow';
-
+          items[index].className += ' rainbow'
         }
       })
 
@@ -143,20 +120,17 @@
       // next, just for fun, let's remove any menu separators (again just at the
       // top level menu). A menu separator is an item with a type : 'separator'
       // property
-
       items = items.filter(function (item) {
-        return item.type !== 'separator';
-      });
+        return item.type !== 'separator'
+      })
 
       // finally we need to return the items array. If we don't, the menu
       // will be empty.
-
-      return items;
-
+      return items
     }
-  };
+  }
 
-  var json = {
+  const json = {
     'array': [1, 2, 3],
     'boolean': true,
     'color': '#82b92c',
@@ -164,10 +138,9 @@
     'number': 123,
     'object': {'a': 'b', 'c': 'd'},
     'string': 'Hello World'
-  };
-
-  var editor = new JSONEditor(container, options, json);
+  }
 
+  const editor = new JSONEditor(container, options, json)
 </script>
 </body>
 </html>
diff --git a/examples/requirejs_demo/scripts/main.js b/examples/requirejs_demo/scripts/main.js
index f05b4e9..d17d738 100644
--- a/examples/requirejs_demo/scripts/main.js
+++ b/examples/requirejs_demo/scripts/main.js
@@ -1,12 +1,12 @@
-var module = '../../../dist/jsoneditor'
+const module = '../../../dist/jsoneditor'
 require([module], function (JSONEditor) {
   // create the editor
-  var container = document.getElementById('jsoneditor')
-  var editor = new JSONEditor(container)
+  const container = document.getElementById('jsoneditor')
+  const editor = new JSONEditor(container)
 
   // set json
   document.getElementById('setJSON').onclick = function () {
-    var json = {
+    const json = {
       array: [1, 2, 3],
       boolean: true,
       null: null,
@@ -19,7 +19,7 @@ require([module], function (JSONEditor) {
 
   // get json
   document.getElementById('getJSON').onclick = function () {
-    var json = editor.get()
+    const json = editor.get()
     window.alert(JSON.stringify(json, null, 2))
   }
 })