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alert(urls.join(",")); We were able to make an array because we iterated through each element in the jQuery object by using the $().each(); method. We are able to access the individual elements and execute jQuery methods against those elements because we wrapped the this variable in a jQuery wrapper, $(), thus making it a jQuery object. Discussion jQuery provides a core method that you can use to loop through your set of selected DOM elements. $().each() is jQuery’s for loop, which will loop through and provide a separate function scope for each element in the set. $().each(); will iterate exclusively through jQuery objects. $().each(); is not the same as the jQuery utility method jQuery.each(object, callback);. The jQuery.each method is a more generalized iterator method that will iterate through both objects and arrays. See jQuery’s online documentation for more information on jQuery.each() at http://docs.jquery.com/Utilities/jQuery.each. In each iteration, we are getting the href attribute of the current element from the main selection. We are able to get the current DOM element by using the this keyword. We then wrap it in the jQuery object, $(this), so that we can perform jQuery methods/ actions against it—in our case, pulling the href attribute from the DOM element. The last action is to assign the href attribute to a global array, urls. Just so we can see what we have, the array URL is joined together with a , and displayed to the user in an alert box. We could also have added the list to an unordered list DOM element for display to the user. More practically, we might want to format the list of URLs into JSON format and send it to the server for processing into a database. Let’s look at another example using $().each();. This example is probably the most obvious use of $().each();. Let’s say we have an unordered list of names, and we want each name to stand out. One way to accomplish this is to set an alternate background color for every other list item: Chapter 3 - Recipe 1 - Looping through a set of selected results .even { background-color: #ffffff; } .odd { background-color: #cccccc; } 54 | Chapter 3: Beyond the Basics
(function($){ $(document).ready(function() { $("ul > li").each(function(i) { if (i % 2 == 1) { $(this).addClass("odd"); } else { $(this).addClass("even"); } }); }); })(jQuery); Family Members Ralph Hope Brandon Jordan Ralphie Figure 3-1 shows the code output. Figure 3-1. Code output As we iterate through each element, we are testing whether the current index, which is passed in as a single argument to the function when executed, modded by 2 is equal to 1. Based on that condition, we either set one CSS class (.odd) or another CSS class (.even). 3.1 Looping Through a Set of Selected Results | 55
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Solutions & Examples for jQuery Dev
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jQuery Cookbook
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jQuery Cookbook by jQuery Community
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2.3 Selecting Elements by Index Ord
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8.5 Passing Dynamic Data to Event H
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16.5 Using HTML Fragments and jQuer
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This is largely what makes somethin
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on client-side optimization techniq
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Tech Editors Karl Swedberg, after h
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What You’ll Learn We’ll start o
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If none of this works, it’s possi
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800-998-9938 (in the United States
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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 40 and 41: "4 inputs" alert('selected' + jQuer
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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 50 and 51: • While the elements selected are
Page 52 and 53: Discussion The cloning method is ac
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Page 56 and 57: jQuery('p').text('Hello World,
Page 59 and 60: 2.0 Introduction CHAPTER 2 Selectin
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Page 65 and 66: Discussion As mentioned, an element
Page 67 and 68: 2.6 Selecting Elements by What They
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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 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()
Page 90 and 91: Figure 3-6. Code output In the prec
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Page 94 and 95: Solution Let’s say you inherit a
Page 96 and 97: If you use this technique, you will
Page 98 and 99: available on the Web. jQuery hosts
Page 100 and 101: Discussion In the preceding example
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Page 104 and 105: }); })(jQuery); 4.3 Filtering Array
Page 106 and 107: Discussion In this example, we have
Page 108 and 109: }); }); })(jQuery); Discussion Upon
Page 110 and 111: Discussion In this recipe, we use t
Page 112 and 113: Solution The if/else statement and
Page 114 and 115: var foo = new Foo( 'bar' ); foo.ale
Page 116 and 117: } $('#province').toggle( value == '
Page 118 and 119: Did jQuery invent chaining? No. jQu
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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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