Categories

.find()

Categories: Tree Traversal

.find( selector )Returns: jQuery

Description: Get the descendants of each element in the current set of matched elements, filtered by a selector, jQuery object, or element.

  • .find( selector )

    version added: 1.0

    selector   A string containing a selector expression to match elements against.

  • .find( jQuery object )

    version added: 1.0

    jQuery object   A jQuery object to match elements against.

  • .find( element )

    version added: 1.0

    element   An element to match elements against.

Given a jQuery object that represents a set of DOM elements, the .find() method allows us to search through the descendants of these elements in the DOM tree and construct a new jQuery object from the matching elements. The .find() and .children() methods are similar, except that the latter only travels a single level down the DOM tree.

The first signature for the .find()method accepts a selector expression of the same type that we can pass to the $() function. The elements will be filtered by testing whether they match this selector.

Consider a page with a basic nested list on it:

<ul class="level-1">
  <li class="item-i">I</li>
  <li class="item-ii">II
    <ul class="level-2">
      <li class="item-a">A</li>
      <li class="item-b">B
        <ul class="level-3">
          <li class="item-1">1</li>
          <li class="item-2">2</li>
          <li class="item-3">3</li>
        </ul>
      </li>
      <li class="item-c">C</li>
    </ul>
  </li>
  <li class="item-iii">III</li>
</ul>

If we begin at item II, we can find list items within it:

$('li.item-ii').find('li').css('background-color', 'red');

The result of this call is a red background on items A, B, 1, 2, 3, and C. Even though item II matches the selector expression, it is not included in the results; only descendants are considered candidates for the match.

Unlike in the rest of the tree traversal methods, the selector expression is required in a call to .find(). If we need to retrieve all of the descendant elements, we can pass in the universal selector '*' to accomplish this.

Selector context is implemented with the .find()method; therefore, $('li.item-ii').find('li') is equivalent to $('li', 'li.item-ii').

As of jQuery 1.6, we can also filter the selection with a given jQuery collection or element. With the same nested list as above, if we start with:

var $allListElements = $('li');

And then pass this jQuery object to find:

$('li.item-ii').find( $allListElements );

This will return a jQuery collection which contains only the list elements that are descendants of item II.

Similarly, an element may also be passed to find:

var item1 = $('li.item-1')[0];
$('li.item-ii').find( item1 ).css('background-color', 'red');

The result of this call would be a red background on item 1.

  • Starts with all paragraphs and searches for descendant span elements, same as $("p span")

    HTML:
    <p><span>Hello</span>, how are you?</p>
    <p>Me? I'm <span>good</span>.</p>
    Code:
    
      $("p").find("span").css('color','red');
    
  • A selection using a jQuery collection of all span tags. Only spans within p tags are changed to red while others are left blue.

    HTML:
    <p><span>Hello</span>, how are you?</p>
      <p>Me? I'm <span>good</span>.</p>
      <div>Did you <span>eat</span> yet?</div>
    CSS:
    
        span { color: blue; }
      
    Code:
    
      var $spans = $('span');
      $("p").find( $spans ).css('color','red');
    
  • Add spans around each word then add a hover and italicize words with the letter t.

    HTML:
    <p>
      When the day is short
      find that which matters to you
      or stop believing
      </p>
    CSS:
    
      p { font-size:20px; width:200px; cursor:default; 
          color:blue; font-weight:bold; margin:0 10px; }
      .hilite { background:yellow; }
      
    Code:
    
      var newText = $("p").text().split(" ").join("</span> <span>");
      newText = "<span>" + newText + "</span>";
    
      $("p").html( newText )
        .find('span')
        .hover(function() { 
          $(this).addClass("hilite"); 
        },
          function() { $(this).removeClass("hilite"); 
        })
      .end()
        .find(":contains('t')")
        .css({"font-style":"italic", "font-weight":"bolder"});