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"4 inputs" alert('selected' + jQuery('input',document.forms[0]).length + ' inputs'); //search within the body element for all input elements using an expression, //alerts "12 inputs" alert('selected' + jQuery('input','body').length + ' inputs'); Discussion It’s also possible, as mentioned in the solution of this recipe, to select documents as the context for searching. For example, it’s possible to search within the context of an XML document that is sent back from doing an XHR request (Ajax). You can find more details about this usage in Chapter 16. 1.5 Filtering a Wrapper Set of DOM Elements Problem You have a set of selected DOM elements in a jQuery wrapper set but want to remove DOM elements from the set that do not match a new specified expression(s) in order to create a new set of elements to operate on. Solution The jQuery filter method, used on a jQuery wrapper set of DOM elements, can exclude elements that do not match a specified expression(s). In short, the filter() method allows you to filter the current set of elements. This is an important distinction from the jQuery find method, which will reduce a wrapped set of DOM elements by finding (via a new selector expression) new elements, including child elements of the current wrapped set. To understand the filter method, let’s examine the following code: link link link link 16 | Chapter 1: jQuery Basics
link link link link //alerts 4 left in the set alert(jQuery('a').filter('.external').length + ' external links'); The HTML page in the code example just shown contains a web page with 10 elements. Those links that are external links are given a class name of external. Using the jQuery function, we select all elements on the page. Then, using the filter method, all those elements that do not have a class attribute value of external are removed from the original set. Once the initial set of DOM elements are altered using the filter() method, I invoke the length property, which will tell me how many elements are now in my new set after the filter has been applied. Discussion It’s also possible to send the filter() method a function that can be used to filter the wrapped set. Our previous code example, which passes the filter() method a string expression, can be changed to use a function instead: alert( jQuery('a') .filter(function(index){ return $(this).hasClass('external');}) .length + ' external links' ); Notice that I am now passing the filter() method an anonymous function. This function is called with a context equal to the current element. That means when I use $(this) within the function, I am actually referring to each DOM element in the wrapper set. Within the function, I am checking each element in the wrapper set to see whether the element has a class value (hasClass()) of external. If it does, Boolean true, then keep the element in the set, and if it doesn’t (false), then remove the element from the set. Another way to look at this is if the function returns false, then the element is removed. If the function returns any other data value besides false, then the element will remain in the wrapper set. You may have noticed that I have passed the function a parameter named index that I am not using. This parameter, if needed, can be used to refer numerically to the index of the element in the jQuery wrapper set. 1.5 Filtering a Wrapper Set of DOM Elements | 17
Page 1 and 2: Solutions & Examples for jQuery Dev
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Page 6 and 7: jQuery Cookbook by jQuery Community
Page 8 and 9: 2.3 Selecting Elements by Index Ord
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Page 14 and 15: This is largely what makes somethin
Page 16 and 17: on client-side optimization techniq
Page 18 and 19: Tech Editors Karl Swedberg, after h
Page 20 and 21: What You’ll Learn We’ll start o
Page 22 and 23: If none of this works, it’s possi
Page 24 and 25: 800-998-9938 (in the United States
Page 26 and 27: traversing and manipulation, browse
Page 28 and 29: • Using the jQuery wrapper and im
Page 30 and 31: The jQuery wrapper set A good major
Page 32 and 33: — Attr — Class — HTML — Tex
Page 34 and 35: alert('jQuery ' + jQuery.fn.jquery)
Page 36 and 37: alert(jQuery('p').text()); }); T
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Page 44 and 45: .end().end().length); //alerts 3
Page 46 and 47: Now, let’s select the second ele
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Page 52 and 53: Discussion The cloning method is ac
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Page 65 and 66: Discussion As mentioned, an element
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Page 71 and 72: These filters can also be used with
Page 73 and 74: Solution As well as passing a selec
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Page 78 and 79: alert(urls.join(",")); We were able
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Page 82 and 83: Figure 3-2. Code output As you can
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Page 86 and 87: Figure 3-4. Code output 3.4 Getting
Page 88 and 89: Discussion The core method index()
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Figure 3-6. Code output In the prec
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ligula. Aenean mattis pulvinar est
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Solution Let’s say you inherit a
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If you use this technique, you will
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available on the Web. jQuery hosts
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Discussion In the preceding example
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.click(function() { // Special clic
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}); })(jQuery); 4.3 Filtering Array
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Discussion In this example, we have
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}); }); })(jQuery); Discussion Upon
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Discussion In this recipe, we use t
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Solution The if/else statement and
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var foo = new Foo( 'bar' ); foo.ale
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} $('#province').toggle( value == '
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Did jQuery invent chaining? No. jQu
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Whether the idea comes from elsewhe
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}; return object; That could also b
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null or undefined, remove the attri
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The +new Date in this code is just
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(function() { var log = [], index =
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The page also contains a large numb
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you could use this: $('.clientX') /
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And you have this HTML code in your
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when you discover the slow parts, y
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A Warning About for..in Loops Never
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Other code here calls maxMagnitude
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matter, but in performance-critical
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console.log( $foo ); $foo.css({ fon
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Solution 1 You’re using the minif
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After the page loads, you are down
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5.19 Writing Unobtrusive JavaScript
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Documentation Tutorials We’ve
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Beware that you don’t make the us
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+ $(document).scrollLeft() }) .show
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Want to read more? You can find thi
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