Pro JavaScript for Web Apps pdf - EBook Free Download

CHAPTER 2 GETTING STARTED• Caution A common mistake is to forget to wrap the JavaScript statements to be executed in a function, whichcauses an odd effect. If you pass a single statement to the ready method, then it will be executed as soon as thebrowser processes the script element. If you pass multiple statements, then the browser will usually report aJavaScript error.The ready method creates a handler for the ready event. I’ll show you more of the way that jQuerysupports events later in this chapter. The ready event is available only for the document object, which iswhy you will see the statements highlighted in the listing in almost every web app that uses jQuery.Selecting and Hiding the Input ElementNow that I have delayed the execution of the JavaScript code until the DOM is ready, I can turn to thenext step in my task, which is to hide the input element that submits the form. Listing 2-4 highlights thestatement from the example that does just this.Listing 2-4. Selecting and Hiding the input Element...$(document).ready(function() {$('#buttonDiv input:submit').hide();$('Submit Order').appendTo("#buttonDiv");})...This is a classic two-part jQuery statement: first I select the elements I want to work with, and then Iapply a jQuery method to modify the selected elements. You may not recognize the selector I have usedbecause the :submit part is one of the selectors that jQuery defines in addition to those in the CSSspecification. Table 2-1 contains the most useful jQuery custom selectors.19www.it-ebooks.info