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Tracks pristine/dirty state of in-browser form controls
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form-change-tracker is a small (less than 2 kB gzipped), dependency-free JavaScript browser library for keeping track of the state (pristine vs. changed) of controls in a DOM-based form.

Using this state (i.e.: via CSS class names added or removed from controls and their associated <label> elements), you can provide visual feedback regarding which controls have changed and which have not. Of course, it will detect if an element is first changed and then changed back to its initial value. Additionally, form-change-tracker automatically manages disabling or enabling a reset button, if there is one in the form, and will call a callback, if you like.

This library is probably not what you need in a project where you already are using some SPA framework (React, Angular, Vue or the like), but is a nice addition for “classical” mainly server-side rendered applications.

Browser support

This library will work (at least) on:

  • Google Chrome Desktop and Android (no particularly new version required)
  • Firefox Desktop and Android (no particularly new version required)
  • Safari Desktop and iOS (no particularly new version required)
  • Microsoft Edge (no particularly new version required)
  • Microsoft IE11

How to set up and use


Depending on your favorite package manager, run either of:

  • npm install @bluem/form-change-tracker
  • yarn add @bluem/form-change-tracker


The library is an ES6 class, so the way to use it depends on your tooling and the browsers you want to support.

Native ES6 module

In your ES6 module, import the library:

import FormChangeTracker from './node_modules/@bluem/form-change-tracker/index.js';

Then, add <script type="module" src="demo.js"></script> to your code.

With Webpack

First, write your code using an ES6 import:

import FormChangeTracker from '@bluem/form-change-tracker';

Then, assuming you have Webpack installed locally in your project:

./node_modules/.bin/webpack -p demo.js --output dist/webpack-bundle.js

Then, add <script src="dist/webpack-bundle.js"></script> to your HTML.

The above command would be sufficient, but of course, you can use a webpack.config.js configuration file.

With Parcel

First, write your code using an ES6 import:

import FormChangeTracker from '@bluem/form-change-tracker';

Then, assuming you have Parcel installed locally in your project:

./node_modules/.bin/parcel build demo.js -o dist/parcel-bundle.js

(Note that you might need to install babel-core)

Finally, simply load the generated file:

<script src="dist/parcel-bundle.js"></script>


The most simple invocation is:

new FormChangeTracker();

This will invoke FormChangeTracker with the default options, which is equivalent to …

new FormChangeTracker({
  selector: 'form',
  classname: 'control-changed',
  confirm: function (callback) {
    if (confirm('Are you sure you want to reset the form and lose unsaved changes?')) {

The options are:

  • selector: A CSS selector (compatible with document.querySelector). The first element that matches is used.
  • element: Instead of a selector, you can directly pass an element (which must be a <form> element)
  • classname: A CSS class name to add to both the control and the corresponding label
  • callback: A function which will be called when an control’s state changes. The function will be given two arguments: first, the control, second a Boolean indicating if the control is now in a dirty/changed state or not.
  • confirm: A confirmation function which will be invoked if the reset button (if there is one in the form) is clicked and the form is dirty. This must be a function which is expected to take a function as argument, which should be invoked if the user confirms.

The confirm property is built this way to make it easy to use some external function or library for this. For instance, this would be the code for integrating SweetAlert:

new FormChangeTracker({
  confirm: function(confirmationCallback) {
        title: "Are you sure?",
        text: "Your unsaved changes will be lost.",
        type: "warning",
        showCancelButton: true,
        confirmButtonColor: "#DD6B55",
        confirmButtonText: "Go ahead",
        closeOnConfirm: true
      function () {'Reset');


As the library is simple, highly browser-oriented and easy to test manually, I chose to remove the tests I had for the 0.* versions. Which means that there are no automated tests of any kind.

Version History


  • Migrated to a native ES6 class
  • Added option callback
  • Removed tests
  • Improved Readme

0.5.1 (2017-06-21)

  • Vanilla JS rewrite of legacy jQuery code (which was a rewrite of legacy Prototype.js code)
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