JSFiddle - React, Tailwind, and code Playground

HTML

<form id="add_item">
    <input type="text" id="text_input" />
    <input type="email" id="email_input" />
    <select id="select_input">
        <option>option 1</option>
        <option>option 2</option>
    </select>
    <input type="radio" id="radio_input" />
    <input type="checkbox" id="checkbox_input" />
    <textarea id="textarea_input">Textarea</textarea>
</form>
<a href="http://jsfiddle.net/M9tnP/16/" target="_top">Leave Page</a>

JavaScript

var dirty = false;
$("form#add_item :input").change(function() {
    //alert("form changed!")
    dirty = true;
});

$("window").on('beforeunload', function() {
    if (dirty) {
        return 'You have unsaved changes! If you leave this page, your changes will be lost.';
    }
});