Monday, 27 November 2017

Jquery .find()

.find()


.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.
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. The expressions allowed include selectors like > p which will find all the paragraphs that are children of the elements in the jQuery object.
Consider a page with a basic nested list on it:
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<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:
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$( "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 most 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:
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var allListElements = $( "li" );
And then pass this jQuery object to find:
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$( "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:
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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.


Examples:

Starts with all paragraphs and searches for descendant span elements, same as $( "p span" )
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<html lang="en">







<head>







  <meta charset="utf-8">







  <title>find demo</title>







  <script src="https://code.jquery.com/jquery-1.10.2.js"></script>







</head>







<body>







 







<p><span>Hello</span>, how are you?</p>







<p>Me? I'm <span>good</span>.</p>







 







<script>







$( "p" ).find( "span" ).css( "color", "red" );







</script>







 







</body>







</html>
at

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