← Back to jQuery Course | Chapter 2: Selectors | Lesson 1 of 10

Basic Selectors

ID selectors target one element by its ID.

In this page:

  1. Select by ID
  2. Select by Class
  3. Select by Element
  4. Combine Selectors
  5. Use a Selector Variable
Syntax
javascript 
$("tagname")
$("#id")
$(".classname")
$("selector1, selector2")
$("*")

Select by ID

An ID selector uses a hash symbol followed by the element's id attribute to select exactly one matching element on the page. Because ids must be unique, this is the most direct and fastest way to target a specific element.

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="title">Page Title</h1>

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

    $("#runBtn").click(function() {
      $("#output").text($("#title").length);
    });

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

Select by Class

A class selector uses a dot followed by the class name, and because many elements can share one class, it returns a jQuery object wrapping every match -- ideal for styling or updating 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="highlight">A</p><p class="highlight">B</p>

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

    $("#runBtn").click(function() {
      $("#output").text($(".highlight").length);
    });

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

Select by Element

An element (tag) selector, like $(p), matches every element with that tag name on the page, which is useful for broad, page-wide changes but can accidentally catch more elements than you intended.

Example: Select by Element

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>One</p><p>Two</p>

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

    $("#runBtn").click(function() {
      $("#output").text($("p").length);
    });

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

Combine Selectors

Separating selectors with a comma, like $('h1, .highlight'), lets you target multiple unrelated groups of elements in a single call instead of writing several separate statements.

Example: Combine Selectors

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>Title</h1>
    <p class="highlight">Text</p>

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

    $("#runBtn").click(function() {
      $("#output").text($("h1, .highlight").length);
    });

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

Use a Selector Variable

Storing a selector string in a variable before passing it to $() keeps your code DRY when you need to reuse the same target in several places, and makes it easy to update the selector in one spot later.

Example: Use a Selector Variable

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">Item</p>

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

    $("#runBtn").click(function() {
      var sel = ".item";
      $("#output").text($(sel).length);
      $(sel).css("color", "teal");
    });

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

Attribute Selectors · Form Selectors · Hierarchy Selectors · Basic Filter Selectors

{# 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. Writing $("title") when the element has id="title", which selects the <title> tag instead of the element; an ID needs $("#title").
  2. Expecting $("#title") to return the element itself; it returns a jQuery object, so use $("#title")[0] or .get(0) for the raw DOM node.
  3. Reusing the same id on several elements, so $("#item") matches only the first one instead of all of them.
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