jquery parents用法

之前一直用find

现在用parents

var w = $("div");

　　w = $("div").parents('.class'); //在Parents中找我们需要的dom节点

　　var f = 'span';
　　var pFindSize = w.find(f).size();
　　if(pFindSize !== 0){
　　　　console.log('find');
　　}

//jquery api eg:

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:

<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:

1	`$( "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:

1	`var allListElements = $( "li" );`

And then pass this jQuery object to find:

1	`$( "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:

1 2	`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" )

<!doctype html>

<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>

Demo:

A selection using a jQuery collection of all span tags. Only spans within p tags are changed to red while others are left blue.

<!doctype html>

<html lang="en">

<head>

<meta charset="utf-8">

<title>find demo</title>

<style>

span {

color: blue;

}

</style>

<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>

<div>Did you <span>eat</span> yet?</div>

<script>

var spans = $( "span" );

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

</script>

</body>

</html>

Demo:

Add spans around each word then add a hover and italicize words with the letter t.

<!doctype html>

<html lang="en">

<head>

<meta charset="utf-8">

<title>find demo</title>

<style>

p {

font-size: 20px;

width: 200px;

color: blue;

font-weight: bold;

margin: 0 10px;

}

.hilite {

background: yellow;

}

</style>

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

</head>

<body>

<p>

When the day is short

find that which matters to you

or stop believing

</p>

<script>

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"

});

</script>

</body>

</html>