Beginning Jquery 2 For Asp.net Developers: Using Jquery 2 With Asp.net Web Forms And Asp.net Mvc by Bipin Joshi


04569681e8e8b25-261x361.jpg Author Bipin Joshi
Isbn 978-1430263043
File size 10.8 Mb
Year 2013
Pages 334
Language English
File format PDF
Category web development


 

For your convenience Apress has placed some of the front matter material after the index. Please use the Bookmarks and Contents at a Glance links to access them. Contents at a Glance About the Author���������������������������������������������������������������������������������������������������������������� xv About the Technical Reviewer������������������������������������������������������������������������������������������ xvii Acknowledgments������������������������������������������������������������������������������������������������������������� xix Introduction����������������������������������������������������������������������������������������������������������������������� xxi ■■Chapter 1: The JavaScript You Need to Know�������������������������������������������������������������������1 ■■Chapter 2: A First Look at jQuery������������������������������������������������������������������������������������33 ■■Chapter 3: ASP.NET Controls and jQuery Selectors����������������������������������������������������������63 ■■Chapter 4: Event Handling���������������������������������������������������������������������������������������������103 ■■Chapter 5: DOM Manipulation and Dynamic Content�����������������������������������������������������135 ■■Chapter 6: Traversal and Other Useful Methods������������������������������������������������������������157 ■■Chapter 7: Effects and Animations��������������������������������������������������������������������������������179 ■■Chapter 8: Ajax Techniques�������������������������������������������������������������������������������������������193 ■■Chapter 9: Creating and Using Plugins��������������������������������������������������������������������������231 ■■Chapter 10: jQuery UI and jQuery Mobile����������������������������������������������������������������������255 ■■Chapter 11: Useful jQuery Recipes for ASP.NET Applications����������������������������������������281 ■■Appendix: Learning Resources��������������������������������������������������������������������������������������301 Index���������������������������������������������������������������������������������������������������������������������������������303 v Introduction Welcome to the exciting world of jQuery! If you’re an ASP.NET developer looking to turbocharge your ASP.NET applications with jQuery, you picked the right book. Modern web applications leverage browsers’ resources through client-side scripting. Although JavaScript is a de facto standard as far as client-side scripting is concerned, there are several libraries built on top of JavaScript that help developers accomplish their job quickly and easily. jQuery is one of the most popular JavaScript libraries available today. If you want to develop Ajax-driven, dynamic, and cross-browser web applications using ASP.NET, understanding jQuery is an invaluable skill. While using jQuery in ASP.NET Web Forms and ASP.NET MVC projects, you need to combine the power of jQuery with server controls, controllers, services, and APIs. It is crucial to understand how jQuery can be used effectively in combination with ASP.NET features and technologies. To that end, this book teaches you how to harness the power of the jQuery library in your ASP.NET Web Forms and MVC applications. It helps you understand the foundations of jQuery from the perspective of an ASP.NET developer in a clear, step-by-step way, so that you can quickly ensure you have this invaluable skill under your belt. Who This Book Is For This book is for ASP.NET web developers who want to tap the power of jQuery in their existing or new web applications. This book doesn’t teach you ASP.NET features. I assume that you’re already comfortable working with ASP.NET and doing web application development in general. All the code samples discussed in this book use C# as the server-side programming language, so you should also know C#. Although no prior knowledge of jQuery is expected, I assume that you’re familiar with the basics of JavaScript. The examples illustrated throughout the book use SQL Server and Entity Framework. Although you need not have a detailed understanding of these technologies, you should at least be familiar with them. The book uses Visual Studio as the development tool. You should know how to work with Visual Studio to perform basic tasks such as creating projects and debugging code. Software Required To work through the examples in this book, you need the following software: • Visual Studio 2013 • SQL Server 2012 • jQuery, jQuery UI, and jQuery Mobile library files • Web browsers: Internet Explorer 9+, Firefox, Chrome, Opera, and Safari Although I used Visual Studio Ultimate 2013 to develop the book’s examples, most of the examples can also be developed using Visual Studio Express 2013 for Web. xxi ■ Introduction All the data-driven examples were developed using SQL Server 2012 Express Edition. I use the Northwind sample database in many examples, and I suggest you install it. You can download the Northwind database and its script from the MSDN downloads web site. I used jQuery 2.0.3 to write the examples presented in this book. You should consider downloading the latest versions of jQuery, jQuery UI, and jQuery Mobile from their official web sites. It’s always a good idea to test the client scripts you write in all the major browsers. So you might consider installing the latest versions of Internet Explorer, Firefox, Chrome, Opera, and Safari. How This Book Is Structured This book is organized into 11 chapters and one appendix. Here’s a quick overview: • Chapter 1 gives you a quick recap of JavaScript programming. You can brush up on your JavaScript skills before taking on jQuery. • Chapter 2 gives you a peek into jQuery. You learn the basics, such as downloading and installing jQuery on your machine. You also develop a simple application in ASP.NET Web Forms and MVC. • Chapter 3 gives you a detailed understanding of jQuery selectors. You learn to match DOM elements using powerful and flexible selectors. This chapter also details techniques to deal with server controls while selecting them in the jQuery code. • Chapter 4 teaches you one of the most commonly used features: event handling. It covers commonly used events such as window, keyboard, and mouse events. Some advanced concepts relating to event handling, such as passing custom data to the event handler, are also covered. • Chapter 5 is about DOM manipulation using jQuery. Topics covered include applying CSS styles, working with attributes, and manipulating DOM elements. • Chapter 6 covers DOM navigation and filtering techniques, including tree traversal, iterating, searching, working with custom data attributes, and more. • Chapter 7 teaches you how to apply jQuery effects and animations to Web Form controls and page elements. You learn to apply fancy effects such as fade-in, fade-out, slide-up and slide-down. You also learn to apply custom animation effects to page elements. • Chapter 8 covers an important topic: Ajax techniques offered by jQuery. This chapter discusses how ASMX web services, WCF services, MVC action methods, and the Web API can be called from the jQuery code. It also discusses the JSON format and its use in Ajax communication. • Chapter 9 discusses plugins—a technique to extend the jQuery core. You can develop plugins to enhance and extend the core functionality offered by jQuery. The chapter discusses the steps involved in building a plugin and gives you some recommendations to be followed during the process. • Chapter 10 gives you an overview of jQuery UI and jQuery Mobile. jQuery UI provides various widgets that you can add to ASP.NET web applications to provide professional user interface elements such as dialogs, menus, accordions, and sliders. jQuery Mobile helps you develop web applications targeted at mobile devices. • Chapter 11 presents a few recipes that you will find useful in real-world applications. The recipes covered include implementing Ajax-based paging, client-side sorting, file upload, autocomplete text box, and cascading drop-down lists. • The Appendix lists some jQuery learning resources. xxii ■ Introduction Downloading the Source Code The complete source code for the book is available for download at the book’s companion web site. Visit http://www.apress.com and go to the book’s information page at http://www.apress.com/9781430263043. You can then download the source code from the Source Code/Downloads section. Contacting the Author You can reach me via my web site: http://www.binaryintellect.net. You can also follow me on popular social-networking web sites such as Facebook and Twitter (visit my web site for details). xxiii Chapter 1 The JavaScript You Need to Know JavaScript is a programming language that adds interactivity and dynamic content to otherwise static HTML pages. Behind most fancy frills such as mouseover effects, animations, drop-down menus, and form validations, you will usually find JavaScript being used in some way or another. jQuery is a JavaScript library that simplifies your client-side programming tasks and uses the same programming constructs as JavaScript for variables, branching, and looping. While writing jQuery code, you often need to use these JavaScript programming constructs. Therefore, before you delve into jQuery programming, you must refresh your JavaScript skills. This chapter is intended to give you a quick overview of commonly used JavaScript features so that you can use the knowledge gained in this chapter in the remainder of the book. If you are already familiar with JavaScript, you can skip this chapter, or glance over its content and jump to the next chapter. Specifically, you will learn how to do the following: • Understand basic programming constructs used in JavaScript for branching and looping • Work with JavaScript variables and data types • Use built-in string, number, and date functions • Create and use your own functions ■■Note  Although this chapter is intended to give you an overview of the JavaScript language, it does not cover all JavaScript features. For more information on JavaScript programming, see https://developer.mozilla.org/en-US/docs/Web/JavaScript. Your First JavaScript Program In this section, you will develop a simple ASP.NET Web Form that makes use of JavaScript to seek a confirmation from the end user. Although the application is not very sophisticated, it does throw light on some basics of JavaScript. Figure 1-1 shows the Web Form you will develop. 1 Chapter 1 ■ The JavaScript You Need to Know Figure 1-1.  Your first JavaScript program As shown in Figure 1-1, the Web Form consists of a couple of Label controls, a TextBox, and a Button server control. Once you enter a name and hit the Submit button, a confirmation dialog is shown that seeks your consent to submit the form. Depending on your choice, either the form submission is canceled or the form is submitted to the server. Upon postback, the entered name is displayed in a Label control. To begin developing this application, create a new ASP.NET Web Application based on the Empty project template using Visual Studio (see Figure 1-2). Figure 1-2.  Creating a new ASP.NET Empty Web Application using Visual Studio 2 Chapter 1 ■ The JavaScript You Need to Know Add a new Web Form to the project and name it FirstJS.aspx. Design the Web Form as shown in Figure 1-1 by dragging and dropping the respective server controls from the toolbox. The HTML and server control markup of the Web Form is shown in Listing 1-1. Listing 1-1.  Markup of FirstJS.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="FirstJS.aspx.cs" Inherits="Chapter_01. FirstJS" %> ...  

First JavaScript Program







  The markup contains two Label controls: one that acts as the prompt for the name text box, and the other that is placed below the Submit button. The server-side click event handler of Button1 simply outputs the name entered by the user in Label2. Listing 1-2 shows this event handler. Listing 1-2.  Submit Button Server-Side Click Event Handler protected void Button1_Click(object sender, EventArgs e) { Label2.Text = "Hello " + TextBox1.Text; }   So far, the application doesn’t use any JavaScript. In the next step, you add some JavaScript code that is invoked when the user clicks the Submit button. To do so, modify the markup of the Submit button as shown here:     You can add the OnClientClick attribute in two ways: you can either switch to the source view of Visual Studio IDE and key in the markup shown in bold letters, or set the OnClientClick property of Button1 in the Properties window. The OnClientClick property is used to specify the client-side (JavaScript) code that is to be executed when the button is clicked. In this case, you set the OnClientClick property to return confirmName(). confirmName() is a custom JavaScript function that you will write next. Go into the section of the Web Form and add a   The   This time, you use another method of the document object: write(). The write() method accepts a string and writes it in the document at the place where the call to write() is placed. In this case, the first call to write() outputs a horizontal rule; the second call outputs the timestamp. Notice how the timestamp is obtained: you use the JavaScript Date object and invoke its toString() method to get a string representation of the current date and time. This completes your code. Run the Web Form in the browser, enter a name in the text box, and click the Submit button. Figure 1-3 shows a sample run of the Web Form. Figure 1-3.  Sample run of the Web Form Notice that the name entered by the user is displayed, followed by new lines and then the message seeking confirmation. Basic Programming Constructs Like most other programming languages such as C# and Visual Basic, JavaScript has its own language constructs. These constructs form the building blocks for writing simple to complex programs. By using these constructs, you accomplish programming tasks such as conditional execution of your code and looping. This section discusses some constructs you will use every day while working with JavaScript. 5 Chapter 1 ■ The JavaScript You Need to Know Statements A JavaScript program consists of one or more statements. Simply put, a statement is an instruction to the JavaScript engine to do something. Every statement ends with a semicolon (;). For example, here are a couple of statements:   document.write("Hello World!"); var textbox = document.getElementById("TextBox1");   The first statement uses the write() method of the document object to output a string: Hello World! The second statement declares a variable named textbox and stores a reference to the TextBox1 DOM element in it. Comments Comments are used to add explanatory text to your program. As a good developer, you should place comments in your code so that you and fellow developers can understand the code at some later stage. JavaScript has two types of comments: single line comments and block comments. The syntax for both of them is exactly the same as C# commenting syntax. The following example makes it clear:   // this is a single line comment   /* This is a block comment That can span multiple lines */   Keep in mind that JavaScript code gets downloaded from the web server to the client browser. Every line of comment that you add to the code also adds to the overall network bandwidth, so you should use ASP.NET’s “minification” feature to strip away comments to make the resulting code compact and tidy. Of course, during development you can place comments as required to ease the overall debugging experience and apply minification to the release version of the JavaScript code. ■■Note  Minification of JavaScript involves many steps, including removal of white spaces, new line characters, comments, and so on. Of course, the minification process preserves the original functionality of the code. Built-in Functions Earlier in this chapter, you created a function called confirmName(). This was a developer defined function. JavaScript also has several built-in functions that you can use in your code. Just like any .NET Framework method, a JavaScript function encapsulates certain functionality so you need not rewrite it. For example, the confirmName() function that you created earlier uses a built-in function, confirm(), which displays a developer defined message to the end user and seeks confirmation in the form of OK and Cancel. Two more JavaScript functions that you will find yourself using often are alert() and prompt(). Let’s modify the confirmName() function to use these two functions. Listing 1-5 shows the modified confirmName() function that makes use of alert() and prompt(). 6 Chapter 1 ■ The JavaScript You Need to Know Listing 1-5.  Using alert() and prompt() function confirmName() { var textbox = document.getElementById("TextBox1"); alert("You will now be asked to enter your name."); var enteredName = prompt("Please enter your name below:", "name goes here..."); var flag = confirm("You entered : " + enteredName + "\n\nDo you wish to continue?"); if (flag) { textbox.value = enteredName; return true; } else { return false; } }   Notice the lines marked in bold. The first line uses alert() to display a message box to the user with a specified text. The alert dialog has an OK button. The second line uses the prompt() function to prompt the user to enter a name. The prompt() function displays a dialog with a text box and has OK and Cancel buttons. The two parameters supplied to prompt() are the prompt text and a default value for the text box. Figure 1-4 shows how these two dialogs are displayed in Chrome. Figure 1-4.  The alert() and prompt() functions displayed in Chrome Notice that the prompt dialog displays a default value in the text box. Once the user clicks OK, the prompt() function returns the entered value (or the default value if the user didn’t make any changes). If the user clicks Cancel, prompt() returns null. In the previous example, after the user clicks the OK button of the prompt dialog, you seek a confirmation from the user about the form submission. If a user wants to submit the form, you assign the enteredName to the text box’s value property. This way, the server-side code still finds the value entered by the user in the prompt dialog. 7 Chapter 1 ■ The JavaScript You Need to Know ■■Tip  JavaScript contains many built-in objects and functions. This section merely touches on a few of them. As you continue through the book, you will come across other built-in functions that will be discussed. Data Types Unlike .NET languages such as C# and Visual Basic, JavaScript doesn’t offer a plethora of data types. Broadly speaking, data involved in JavaScript can be of the string, number, Boolean, and object data types. String The string data type is used often in JavaScript programs. JavaScript strings are enclosed in either double quotes (“...”) or single quotes ('...'). This is unlike C#, in which strings are always enclosed in double quotes, and a character is enclosed in single quotes. A string enclosed in quotes can include quotes as part of the string data. However, you need to use the escape character (\) to embed quotes into a string. The following are a few examples of JavaScript strings:   "Hello World!" 'Hello Universe!' "Hello 'Tom'" 'Hello "Jerry"' "Hello \"Tom & Jerry\""   The first two examples are quite straightforward. The third string embeds single quotes inside a double quote, and the third string embeds double quotes inside single quotes. Although this process doesn’t create any problem for the code, if you want to embed double quotes in a string that uses double quotes as the enclosure, you need to escape the embedded double-quote characters (as shown in the last example). The same principle applies to single-quote characters embedded in a string enclosed by single quotes. Number Just like C#, you can use numbers in JavaScript. Unlike C#, in which there are different data types such as int, float, decimal, and double to represent a number, JavaScript treats all types of numeric values as numbers. A number can be an integer or a floating point number, and it can be positive or negative. Unlike strings, numbers don’t use enclosures. Following are a few examples of JavaScript numbers:   100 1.23 -200  Boolean Boolean data types can hold one of the two values: true or false. Commonly Boolean values are used while conditionally checking something. They are also used as flags to indicate some state within a program. JavaScript Boolean values are quite similar to the C# bool data type. 8 Chapter 1 ■ The JavaScript You Need to Know Object In addition to the string, number, and Boolean data types, JavaScript code often uses objects. An object can be built-in or developer defined. For example, while working with dates and times, you use the JavaScript Date object. While making Ajax calls to the server you often send and receive data as a custom object. These are developer defined objects and are often referred to as JavaScript Object Literals or plain objects. Variables In .NET languages such as C#, you normally declare a variable of a specific data type to store some value. For example, a variable of type int is declared in C# as follows:   int a = 100;   Unlike C#, JavaScript doesn’t allow you to declare a variable with a specific data type; it has the keyword var for declaring any type of variable. Depending on whether you store a string, a number, or a Boolean value in the variable, it is treated as a string, a number, or a Boolean. Consider the following variables:   var name = "Tom"; var age = 25; var flag = true;   In the preceding example, name is a string variable, age is a numeric variable, and flag is a Boolean variable. It is not necessary to assign a value to a variable at the time of declaring it. If no value is assigned to a variable, it is treated as undefined. Have a look at the following code fragment:   var myvariable; alert(typeof myvariable); myvariable = "Tom"; alert(typeof myvariable); myvariable = 100; alert(typeof myvariable);   The first line of the code block declares a variable named myvariable. It then uses alert() and the typeof operator to display the type of the variable. Because myvariable is not yet assigned, the first alert() displays ‘undefined’. Then the code assigns a string "Tom" to myvariable, and the second alert() displays the type of myvariable as ‘string’. Then a value of 100 is assigned to myvariable, and the third alert() displays the type of myvariable as ‘number’. Notice that the same variable is treated first as a string and then as a number, depending on the value it holds. ■■Caution  Although you can store different types of data in the same variable (string and number, for example), you should avoid doing so because it makes your code hard to understand and can introduce errors that are difficult to trace. 9 Chapter 1 ■ The JavaScript You Need to Know Although you can name your JavaScript variables anything you want, the names you choose must adhere to the following basic rules: • Just like C#, JavaScript variable names are case sensitive (e.g., FNAME and fname are treated as different variables). • Variable names can contain only letters, numbers, _, and $ (e.g., age, _fname, $age2), • Variable names must begin with a letter, _, or $ (e.g., 123age is an invalid variable name). ■■Caution It is important that you give readable and meaningful names to JavaScript variables; otherwise, your code may become difficult to understand. Also, use a consistent naming convention for your variables throughout the application. Arrays JavaScript arrays allow you to store multiple values together in the form of a list. An array consists of zero or more items called elements. Each element is capable of storing a value. An array element can be accessed by its sequence number, called the array index, which starts from 0 (the first element can be accessed at index 0, the second at index 1, and so on). The total number of elements in an array is referred to as its length or size. Although JavaScript arrays are similar to C# arrays in many ways, C# arrays are fixed in size, and you can’t add or remove array elements dynamically. JavaScript allows you to add or remove elements even after an array is declared, dynamically changing its size. Arrays come in handy when you are dealing with too many variables that are related. For example, suppose that you are dealing with a calendaring application that deals with month names. One option is to declare 12 independent variables to hold the month names (January, February, and so on). Although this is possible, doing so makes your code difficult because you need to track 12 different variables. Alternatively you can declare an array and store all 12 month names in it. Another example is when you don’t know the number of variables in advance. In such cases, arrays can be useful because you can dynamically add data to them. To understand how arrays are created and used, let’s develop a simple Web Form (see Figure 1-5). Figure 1-5.  Web Form dealing with arrays 10 Chapter 1 ■ The JavaScript You Need to Know As shown in Figure 1-5, the Web Form consists of a text box and three button controls. Clicking the Store button stores the value specified in the text box into an array. The text box serves two purposes: it specifies a string that gets stored in the array and specifies an array index while retrieving an array element. Clicking the Remove button removes the last array element (the array gets truncated from the bottom, one element at a time). Clicking the Retrieve button retrieves an array element whose index is specified in the text box. At the bottom of the Web Form is a Label control that displays the total number of elements in the array at a given point in time. Listing 1-6 shows the relevant markup from the Web Form. Listing 1-6.  Markup of Web Form Dealing with Arrays




  Notice the OnClientClick property of the button controls. It is set to call the storeData(), retrieveData(), and removeData() JavaScript functions, respectively. These three functions go in a