Event Delegation

Event Delegation: free step-by-step lesson with examples, common mistakes, and interview tips — part of jQuery Tutorial on Toolliyo Academy.

8 min read Updated 8/23/2026

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jQuery Tutorial · Lesson 29 of 100

Event Delegation

Setup & DOM ✓ → Events Effects AJAX → Perf & Integrate → Ship & Projects

Events Effects AJAX · 2 — Interact · ~6 min · Events

What is this?

Delegate with $(parent).on("click", "childSelector", handler) so elements added later still match. The listener stays on a stable parent; this is the matched child.

Why should you care?

QueryVerse tables append rows after AJAX — direct binds on current rows miss new ones.

See it live — copy this example

Examples include the jQuery 3.7 CDN. Paste into an HTML file or use Run Example to preview.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>QueryVerse</title>
  <style>
    body { font-family: system-ui, sans-serif; margin: 1.25rem; }
    .box { padding: .75rem; border: 1px solid #ccc; border-radius: 8px; margin: .5rem 0; }
    .muted { color: #666; }
    button { margin-right: .35rem; margin-top: .35rem; }
    input, select, textarea { margin: .25rem 0; }
    table { border-collapse: collapse; width: 100%; }
    th, td { border: 1px solid #ddd; padding: .4rem .55rem; text-align: left; }
    .hidden { display: none; }
    .row-odd { background: #f7f7f7; }
    .active { font-weight: 700; }
    .toast { background: #111; color: #fff; padding: .5rem .75rem; border-radius: 6px; }
  </style>
</head>
<body>
  <ul id="todos" class="box">
    <li><button type="button" class="del">x</button> Task A</li>
  </ul>
  <button type="button" id="add">Add task</button>
<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
<script>
$(function () {
  var n = 1;
  $('#todos').on('click', '.del', function () {
    $(this).closest('li').remove();
  });
  $('#add').on('click', function () {
    n += 1;
    $('#todos').append(
      $('<li/>').append($('<button type="button" class="del"/>').text('x')).append(' Task ' + n)
    );
  });
});
</script>
</body>
</html>

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>QueryVerse</title>
  <style>
    body { font-family: system-ui, sans-serif; margin: 1.25rem; }
    .box { padding: .75rem; border: 1px solid #ccc; border-radius: 8px; margin: .5rem 0; }
    .muted { color: #666; }
    button { margin-right: .35rem; margin-top: .35rem; }
    input, select, textarea { margin: .25rem 0; }
    table { border-collapse: collapse; width: 100%; }
    th, td { border: 1px solid #ddd; padding: .4rem .55rem; text-align: left; }
    .hidden { display: none; }
    .row-odd { background: #f7f7f7; }
    .active { font-weight: 700; }
    .toast { background: #111; color: #fff; padding: .5rem .75rem; border-radius: 6px; }
  </style>
</head>
<body>
  <ul id="todos" class="box">
    <li><button type="button" class="del">x</button> Task A</li>
  </ul>
  <button type="button" id="add">Add task</button>
<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
<script>
$(function () {
  var n = 1;
  $('#todos').on('click', '.del', function () {
    $(this).closest('li').remove();
  });
  $('#add').on('click', function () {
    n += 1;
    $('#todos').append(
      $('<li/>').append($('<button type="button" class="del"/>').text('x')).append(' Task ' + n)
    );
  });
});
</script>
</body>
</html>

Result