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CSS Selectors This section is about CSS Selectors, the importance of knowing what DOM is and learning to select elements of all kinds in different ways. CSS selectors play crucial part in jQuery development. Many people are comfortable with just learning a few selectors. But using selectors in combination with jQuery functions further enable us to make complex selections. For example next, prev and parent functions let us quickly jump from one HTML element to the next. You want to learn as many selectors as possible if you want to increase your productivity. But don’t learn them all at once. Experiment with one selector at a time, and build your knowledge on your past experience. Let’s consider some of the very basic jQuery selectors. The green areas indicate the area of a web page being selected by the corresponding jQuery code displayed below each example: $(‘body’); $(‘#orange’); or $(‘div#orange’); or $(‘body div#orange’); $(‘#orange’).parent(); In the first example we select an element by tag name BODY. In this case, we are selecting the entire body tag. Notice that the children of BODY are not selected only BODY is. The second example uses the # symbol which selects elements by id attribute. In this example when id = “orange”. All three selectors in this example do exactly the same thing but with a different level of accuracy. #orange selects any element with that id but div#orange selects a div element with that id. Remember that there can be only one unique id per element. Third example shows how we can select BODY by referring to it as the parent of a child within it using the function parent(). The DIV in this instance is a child of the parent tag BODY. The function parent() is part of a set of functions for traversing nested HTML tags within the DOM (Document Object Model). Other traversing functions exist such as next() and prev() which will be discussed shortly. CSS Selectors operate on the DOM structure of the entire document starting at the very top. $(“*”) selector selects all tags, even ones above . 75
What Kind of Elements Can You Select? jQuery selectors can select pretty much any HTML element. And if you understand the basics of DOM (Document Object Model), you are at a great advantage. Using your knowledge of DOM and jQuery selectors together can significantly reduce the time you spend developing dynamic JavaScript applications. Here is the basic idea of the DOM. It looks like a tree. The HTML code equivalent of this DOM structure is displayed below the diagram. A Clockwork Orange A Movie By Stanley Kubrick 76
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“ Second Revision. July 2012 Unde
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Prototype, JavaScript Objects and J
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Thought transcends matter. When we
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Preface The purpose of this book is
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A Lesson in Creativity The web deve
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I love jQuery because it allows me
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Improving Page Load Performance The
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Determining the Placement of Intern
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JavaScript 1. The only language peo
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What is JavaScript? Web designers u
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As you can see, variables can be as
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The example above will first execut
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Only variables and events should be
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Notice that variables a and b are c
Page 29 and 30: What Exactly is a JavaScript Variab
Page 31 and 32: A variable allocates enough data st
Page 33 and 34: Do you want to really understand pr
Page 35 and 36: What is a Variable? Variables can b
Page 37 and 38: In order to understand bitwise logi
Page 39 and 40: At first this might seem confusing.
Page 41 and 42: Let’s display the variable “a
Page 43 and 44: What’s important is the return va
Page 45 and 46: Inserting Form Values into MySQL Da
Page 47 and 48: I like code that you can “read”
Page 49 and 50: An object is created from a class.
Page 51 and 52: Dynamic Prototype-based Objects in
Page 53 and 54: Without knowing anything at all abo
Page 55 and 56: More About JSON JSON is a data inte
Page 57 and 58: In some programming languages the t
Page 59 and 60: JavaScript from scratch. If you are
Page 61 and 62: property access operator - the . (d
Page 63 and 64: Why does jQuery do exactly the same
Page 65 and 66: Learning jQuery The greatest thing
Page 67 and 68: If this sounds like you, then you w
Page 69 and 70: Web App Initialization To initializ
Page 71 and 72: In JavaScript, we can define variab
Page 73 and 74: As mentioned above, to an experienc
Page 75 and 76: Including jQuery In Your Source Cod
Page 77 and 78: Including jQuery as an External CDN
Page 79: Including jQuery UI In the Starting
Page 83: To traverse the DOM and make sure t
Page 86 and 87: Here is a basic inline CSS example
Page 88 and 89: Because the DIV element has ID of
Page 90 and 91: After selecting all of these input
Page 92 and 93: Figure 1 Mentality of a beginner jQ
Page 94 and 95: Whose Children Are These? If we are
Page 96 and 97: Next, let’s explore the possibili
Page 98 and 99: jQuery Events Because jQuery is so
Page 100 and 101: Of course, the effects of binding a
Page 102 and 103: Using toggle() Events Toggling betw
Page 104 and 105: Speed Up Your jQuery Code jQuery is
Page 106 and 107: Let’s now look at the jQuery way
Page 108 and 109: Practical jQuery Lessons Instead of
Page 110 and 111: There is a solution to this problem
Page 112 and 113: jQuery provides a secondary way of
Page 114 and 115: Lesson 3: Callback Functions All jQ
Page 116 and 117: For example, the following statemen
Page 118 and 119: As you may know an object can conta
Page 120 and 121: Notice that when we do it this way,
Page 122 and 123: Alternatively, we can create the pa
Page 124 and 125: if (“light”.match(/darkness/) =
Page 126 and 127: jQuery and Regular Expressions In p
Page 128 and 129: This is probably as simple as it ge
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The following example will demonstr
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Making Good CSS Buttons This tutori
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Sometimes it makes sense to make th
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1. Specify javascript: return false
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Our goal is to match the button wit
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So far, we have briefly discussed t
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Note from the Author Looks like you
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