← Back to jQuery Course | Chapter 3: Events | Lesson 8 of 11

Event Propagation and Bubbling

Events normally move from the target toward its parent elements.

In this page:

  1. Bubbling
  2. Stop Propagation
  3. Parent and Child
  4. Prevent Bubbling
  5. Delegated Events
Syntax
javascript 
$(selector).on("eventName", function (event) {
  event.stopPropagation();
});

Bubbling

An event fired on a child element travels upward through its ancestor elements unless something stops it -- this upward travel is called bubbling.

Example: Bubbling

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <style>
    button { padding:6px 14px; margin:4px; background:#2c6aa0; color:white; border:none; border-radius:4px; cursor:pointer; }
    #resetBtn { background:white; color:#2c6aa0; border:1px solid #2c6aa0; }
    #output { margin-top:10px; padding:8px; border:1px solid #ccc; border-radius:4px; background:#f7f7f7; font-family:monospace; min-height:24px; }
    #demo :where(p, div, span, li, h1, h2, h3, h4, td, th, blockquote, label, section, article, aside) { border:1px solid #4a7fb5; background:#eaf2fb; padding:6px 10px; margin:4px 0; border-radius:4px; }
    #demo :where(ul, ol) { border:1px dashed #888; background:#fafafa; padding:8px 8px 8px 32px; margin:6px 0; }
    #demo :where(table) { border-collapse:collapse; }
    #demo :where(td, th) { border-radius:0; }
    #demo :where(input, select, textarea) { margin:4px 0; }
  </style>
</head>
<body>
  <button id="resetBtn">Reset</button>
  <section id="demo">
    <div id="outer"><button id="inner">Click</button></div>

  </section>
  <div id="output"></div>
  <script>
    var original = $("#demo").html();

    function init() {
      $("#outer").on("click", function() { $("#output").append($("<div>").text("Outer handler ran")); });
      $("#inner").on("click", function() { $("#output").append($("<div>").text("Inner handler ran")); });
    }
    init();

    $("#resetBtn").click(function() {
      $("#demo").html(original);
      $("#output").empty();
      init();
    });
  </script>
</body>
</html>

Stop Propagation

Calling event.stopPropagation() inside a handler stops the event from continuing upward, so any handlers attached to parent elements for that same event never run.

Example: Stop Propagation

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <style>
    button { padding:6px 14px; margin:4px; background:#2c6aa0; color:white; border:none; border-radius:4px; cursor:pointer; }
    #resetBtn { background:white; color:#2c6aa0; border:1px solid #2c6aa0; }
    #output { margin-top:10px; padding:8px; border:1px solid #ccc; border-radius:4px; background:#f7f7f7; font-family:monospace; min-height:24px; }
    #demo :where(p, div, span, li, h1, h2, h3, h4, td, th, blockquote, label, section, article, aside) { border:1px solid #4a7fb5; background:#eaf2fb; padding:6px 10px; margin:4px 0; border-radius:4px; }
    #demo :where(ul, ol) { border:1px dashed #888; background:#fafafa; padding:8px 8px 8px 32px; margin:6px 0; }
    #demo :where(table) { border-collapse:collapse; }
    #demo :where(td, th) { border-radius:0; }
    #demo :where(input, select, textarea) { margin:4px 0; }
  </style>
</head>
<body>
  <button id="resetBtn">Reset</button>
  <section id="demo">
    <div id="outer"><button id="inner">Click</button></div>

  </section>
  <div id="output"></div>
  <script>
    var original = $("#demo").html();

    function init() {
      $("#outer").on("click", function() { $("#output").append($("<div>").text("Outer handler ran")); });
      $("#inner").on("click", function(event) {
        event.stopPropagation();
        $("#output").append($("<div>").text("Inner handler ran, stopped bubbling"));
      });
    }
    init();

    $("#resetBtn").click(function() {
      $("#demo").html(original);
      $("#output").empty();
      init();
    });
  </script>
</body>
</html>

Parent and Child

Because of bubbling, both a child element's own handler and any handler on its ancestors can respond to the same single click, running in order from the innermost element outward.

Example: Parent and Child

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <style>
    button { padding:6px 14px; margin:4px; background:#2c6aa0; color:white; border:none; border-radius:4px; cursor:pointer; }
    #resetBtn { background:white; color:#2c6aa0; border:1px solid #2c6aa0; }
    #output { margin-top:10px; padding:8px; border:1px solid #ccc; border-radius:4px; background:#f7f7f7; font-family:monospace; min-height:24px; }
    .btn { display:inline-block; padding:6px 14px; margin:4px; background:#2c6aa0; color:white; border-radius:4px; cursor:pointer; font:13px sans-serif; }
    #resetBtn.btn { background:white; color:#2c6aa0; border:1px solid #2c6aa0; }
    #demo :where(p, div, span, li, h1, h2, h3, h4, td, th, blockquote, label, section, article, aside) { border:1px solid #4a7fb5; background:#eaf2fb; padding:6px 10px; margin:4px 0; border-radius:4px; }
    #demo :where(ul, ol) { border:1px dashed #888; background:#fafafa; padding:8px 8px 8px 32px; margin:6px 0; }
    #demo :where(table) { border-collapse:collapse; }
    #demo :where(td, th) { border-radius:0; }
    #demo :where(input, select, textarea) { margin:4px 0; }
  </style>
</head>
<body>
  <span id="resetBtn" class="btn" role="button">Reset</span>
  <section id="demo">
    <div id="card"><button id="btn">Click</button></div>

  </section>
  <div id="output"></div>
  <script>
    var original = $("#demo").html();

    function init() {
      $("#btn").on("click", function() { $("#output").append($("<div>").text("1: button handler")); });
      $("#card").on("click", function() { $("#output").append($("<div>").text("2: card handler")); });
    }
    init();

    $("#resetBtn").click(function() {
      $("#demo").html(original);
      $("#output").empty();
      init();
    });
  </script>
</body>
</html>

Prevent Bubbling

stopPropagation() is the tool to reach for specifically when a child element's own action -- like a button inside a clickable card -- shouldn't also trigger whatever the card's own click handler does.

Example: Prevent Bubbling

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <style>
    button { padding:6px 14px; margin:4px; background:#2c6aa0; color:white; border:none; border-radius:4px; cursor:pointer; }
    #resetBtn { background:white; color:#2c6aa0; border:1px solid #2c6aa0; }
    #output { margin-top:10px; padding:8px; border:1px solid #ccc; border-radius:4px; background:#f7f7f7; font-family:monospace; min-height:24px; }
    #demo :where(p, div, span, li, h1, h2, h3, h4, td, th, blockquote, label, section, article, aside) { border:1px solid #4a7fb5; background:#eaf2fb; padding:6px 10px; margin:4px 0; border-radius:4px; }
    #demo :where(ul, ol) { border:1px dashed #888; background:#fafafa; padding:8px 8px 8px 32px; margin:6px 0; }
    #demo :where(table) { border-collapse:collapse; }
    #demo :where(td, th) { border-radius:0; }
    #demo :where(input, select, textarea) { margin:4px 0; }
  </style>
</head>
<body>
  <button id="resetBtn">Reset</button>
  <section id="demo">
    <div id="card">Card <button id="btn">Delete</button></div>

  </section>
  <div id="output"></div>
  <script>
    var original = $("#demo").html();

    function init() {
      $("#card").on("click", function() { $("#output").append($("<div>").text("Card clicked")); });
      $("#btn").on("click", function(event) {
        event.stopPropagation();
        $("#output").append($("<div>").text("Button deleted, card click suppressed"));
      });
    }
    init();

    $("#resetBtn").click(function() {
      $("#demo").html(original);
      $("#output").empty();
      init();
    });
  </script>
</body>
</html>

Delegated Events

Event delegation deliberately relies on bubbling rather than fighting it: instead of attaching a handler to every child, you attach one handler to a shared parent and use the bubbled event's target to figure out which child was actually interacted with.

Example: Delegated Events

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <style>
    button { padding:6px 14px; margin:4px; background:#2c6aa0; color:white; border:none; border-radius:4px; cursor:pointer; }
    #resetBtn { background:white; color:#2c6aa0; border:1px solid #2c6aa0; }
    #output { margin-top:10px; padding:8px; border:1px solid #ccc; border-radius:4px; background:#f7f7f7; font-family:monospace; min-height:24px; }
    #demo :where(p, div, span, li, h1, h2, h3, h4, td, th, blockquote, label, section, article, aside) { border:1px solid #4a7fb5; background:#eaf2fb; padding:6px 10px; margin:4px 0; border-radius:4px; }
    #demo :where(ul, ol) { border:1px dashed #888; background:#fafafa; padding:8px 8px 8px 32px; margin:6px 0; }
    #demo :where(table) { border-collapse:collapse; }
    #demo :where(td, th) { border-radius:0; }
    #demo :where(input, select, textarea) { margin:4px 0; }
  </style>
</head>
<body>
  <button id="resetBtn">Reset</button>
  <section id="demo">
    <ul id="list"><li>Item 1</li></ul>

  </section>
  <div id="output"></div>
  <script>
    var original = $("#demo").html();

    function init() {
      $("#list").on("click", "li", function(event) {
        $("#output").append($("<div>").text("Clicked: " + event.target.textContent));
      });
    }
    init();

    $("#resetBtn").click(function() {
      $("#demo").html(original);
      $("#output").empty();
      init();
    });
  </script>
</body>
</html>
Related Topics

The jQuery Event Object · Event Binding with on() · The Hover Event · Document Ready Event

{# common_mistakes/chapter_summary/browser_support: on Hindi pages the view already swaps in the hi_ translation fields (or blanks these out if untranslated), so this renders correctly for both languages without a lang_code check here. #}
Common Mistakes
  1. Being surprised that clicking the inner button also runs the outer #outer handler, because events bubble up to every ancestor by default.
  2. Calling event.stopPropagation() and assuming it also cancels the default action, such as a link navigating, when that needs event.preventDefault().
  3. Using stopPropagation() to fix a stray handler, which also blocks delegated handlers and other code higher up that legitimately needs the event.
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