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 $()function. The elements will be filtered by testing whether they match this selector. The expressions allowed include selectors like > p which will find all the paragraphs that are children of the elements in the jQuery object.
Consider a page with a basic nested list on it:
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<ul class="level-1"> <li class="item-i">I</li> <li class="item-ii">II <ul class="level-2"> <li class="item-a">A</li> <li class="item-b">B <ul class="level-3"> <li class="item-1">1</li> <li class="item-2">2</li> <li class="item-3">3</li> </ul> </li> <li class="item-c">C</li> </ul> </li> <li class="item-iii">III</li></ul> |
If we begin at item II, we can find list items within it:
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$( "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 $( "p span" )
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<!doctype html><html lang="en"><head> <meta charset="utf-8"> <title>find demo</title> <script src="https://code.jquery.com/jquery-1.10.2.js"></script></head><body><p><span>Hello</span>, how are you?</p><p>Me? I'm <span>good</span>.</p><script>$( "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.
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<!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.
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<!doctype html><html lang="en"><head> <meta charset="utf-8"> <title>find demo</title> <style> p { font-size: 20px; 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> |