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jQuery Syntax

The basic jQuery pattern selects an element and then calls a method on it.

In this page:

  1. Basic Syntax
  2. Select by ID
  3. Select by Class
  4. Change CSS
  5. Hide and Show
Syntax
javascript 
$(selector).action();
$(selector).action(parameter);

Basic Syntax

Every jQuery statement follows the same shape -- $(selector).action() -- wrap a selector in the dollar function, then chain the operation you want.

Example: Basic Syntax

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
    <style>
    #demo { background: steelblue; color: #1a1a1a; padding: 10px; border-radius: 4px; }
    </style>
  <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">
    <p id="demo">Text</p>
    <button id="btn">Hide</button>
    <div id="output"></div>

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

    function init() {
      $("#btn").on("click", function() {
        $("#demo").hide();
        $("#output").text("Paragraph hidden");
      });
    }
    init();

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

Select by ID

An ID is unique per page by HTML convention, so a hash-prefixed selector like $('#header') is the fastest and most precise way to grab exactly one element when you know its id attribute.

Example: Select by ID

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="runBtn">Run</button>
  <button id="resetBtn">Reset</button>
  <section id="demo">
    <h1 id="header">Title</h1>

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

    $("#runBtn").click(function() {
      $("#header").css("color", "purple");
    });

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

Select by Class

Classes can be reused across many elements, so a dot-prefixed selector like $('.item') returns a jQuery object wrapping every element sharing that class, letting you act on a whole group at once.

Example: Select by Class

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="runBtn">Run</button>
  <button id="resetBtn">Reset</button>
  <section id="demo">
    <p class="item">One</p>
    <p class="item">Two</p>

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

    $("#runBtn").click(function() {
      $(".item").css("color", "green");
    });

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

Change CSS

The .css() method reads or sets an individual CSS property directly through JavaScript, which is handy for quick style tweaks but is usually better replaced with toggling a class for anything more than a one-off change.

Example: Change CSS

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <style>
    #box { background:steelblue; color:#1a1a1a; padding:10px; border-radius:4px; display:inline-block; margin:10px 0; }
    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="runBtn">Run</button>
  <button id="resetBtn">Reset</button>
  <section id="demo">
    <p id="box">Styled</p>

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

    $("#runBtn").click(function() {
      $("#output").text(String($("#box").css("font-size")));
      $("#box").css("font-size", "20px");
    });

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

Hide and Show

The .hide() and .show() methods toggle an element's display style between none and its previous value, giving you a simple way to reveal or conceal content without writing any CSS yourself.

Example: Hide and Show

javascript 
<!DOCTYPE html>
<html>
<head>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
    <style>
    #box { background: steelblue; color: #1a1a1a; padding: 10px; border-radius: 4px; }
    </style>
  <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">
    <p id="box">Toggle me</p>
    <button id="hideBtn">Hide</button>
    <button id="showBtn">Show</button>
    <div id="output"></div>

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

    function init() {
      $("#hideBtn").click(function() {
        $("#box").hide();
        $("#output").text("hide() called");
      });
      $("#showBtn").click(function() {
        $("#box").show();
        $("#output").text("show() called");
      });
    }
    init();

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

Adding jQuery to a Webpage · Document Ready Event · What is jQuery · jQuery CDN Fallbacks

{# 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. Forgetting the # or . prefix, as in $("header"), which selects <header> tags instead of the element with id="header".
  2. Leaving out the action after the selector, as in $("#demo") alone, which selects the element but changes nothing.
  3. Expecting .css() to return the element when setting: $("#demo").css("color", "red") returns the jQuery object, while .css("color") with one argument returns a string.
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