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c# barcode maker Implementing AJAX with jQuery in Visual C#
Implementing AJAX with jQuery Make QR Code In C#.NET Using Barcode creation for VS .NET Control to generate, create QR Code ISO/IEC18004 image in Visual Studio .NET applications. www.OnBarcode.comQR Code ISO/IEC18004 Decoder In Visual C# Using Barcode reader for .NET framework Control to read, scan read, scan image in VS .NET applications. www.OnBarcode.comAs you saw in Lesson 1, you can use AJAX to call back to the server from the client, get a response, and then update only a portion of the page without doing a refresh. This makes for a better, more interactive user experience. However, Lesson 1 relied on the ASP.NET AJAX Extensions controls to handle the details of setting up the client-to-server calls and the page update. The jQuery library provides similar AJAX functionality but does so by calling web services you define. You can call a stand-alone web service from jQuery and then use the results to update a portion of the page (without causing a refresh). Alternatively, you can write your code to call back to just the page itself and execute a method in the same way. You will take a look at both of these options. Painting Barcode In Visual C# Using Barcode printer for .NET framework Control to generate, create barcode image in .NET applications. www.OnBarcode.comDecode Bar Code In C# Using Barcode scanner for VS .NET Control to read, scan read, scan image in .NET framework applications. www.OnBarcode.comChAPTER 9
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Encoding QR Code In Visual Basic .NET Using Barcode generation for Visual Studio .NET Control to generate, create QR Code image in .NET framework applications. www.OnBarcode.comPaint Bar Code In Visual C#.NET Using Barcode printer for .NET Control to generate, create bar code image in .NET framework applications. www.OnBarcode.comCalling a Web Service with $.ajax() Bar Code Maker In C#.NET Using Barcode drawer for .NET framework Control to generate, create barcode image in Visual Studio .NET applications. www.OnBarcode.comPainting ANSI/AIM Code 39 In Visual C#.NET Using Barcode drawer for VS .NET Control to generate, create Code-39 image in VS .NET applications. www.OnBarcode.comThe jQuery.ajax() method enables you to call a web service and then update your page with the results. This method performs an asynchronous HTTP request, passes data to the request, and gets the results. You can use this method for a variety of tasks, including loading and executing a .js file, posting data to a web form, getting the HTML of a page, and sending and receiving XML data. The typical use, however, is posting to web services for partial page updates. This method takes several name-value pairs as a parameter, called settings. The settings include the URL of your request, the content-type, the HTTP method (GET or POST), and the user name and password of the request. In fact, there are more than 20 settings with which you can work. Let s look at an example of using jQuery to call a typical ASP.NET web service (ASMX file). Note that web services are covered in detail in the 10. In this simple example, the web service takes an employeeId as a parameter and returns a name as a result. The first step is to set up the web service. The following code shows an example. Draw Matrix Barcode In C#.NET Using Barcode encoder for .NET Control to generate, create 2D Barcode image in VS .NET applications. www.OnBarcode.comCreating UPC Case Code In Visual C# Using Barcode drawer for VS .NET Control to generate, create UPC Case Code image in VS .NET applications. www.OnBarcode.comSample of Visual Basic Code <System.Web.Script.Services.ScriptService()> _ Public Class EmployeeServiceVb Inherits System.Web.Services.WebService <WebMethod()> _ Public Function GetEmployee(ByVal employeeId As String) As String 'simulate employee name lookup Return "Jane Developer" End Function End Class Sample of C# Code [System.Web.Script.Services.ScriptService] public class EmployeeService : System.Web.Services.WebService { [WebMethod] public string GetEmployee(string employeeId) { //simulate employee name lookup return "Jane Developer"; } } Generating USS Code 128 In None Using Barcode creator for Software Control to generate, create Code128 image in Software applications. www.OnBarcode.comQR Code ISO/IEC18004 Scanner In VB.NET Using Barcode recognizer for Visual Studio .NET Control to read, scan read, scan image in VS .NET applications. www.OnBarcode.comNotice the ScriptService attribute in the code. You adorn your code with this attribute to indicate that the service can be called from client-side script such as jQuery. The next step is to make the AJAX call from a webpage. Assume that you have a form (based on a master page) that allows a user to enter an employee ID and then click a search button with the ButtonSearch ID to trigger the client-side JavaScript. You would then write the jQuery code shown on the following page. UCC - 12 Maker In None Using Barcode maker for Office Word Control to generate, create GS1-128 image in Word applications. www.OnBarcode.comGenerating Barcode In Objective-C Using Barcode drawer for iPhone Control to generate, create bar code image in iPhone applications. www.OnBarcode.comLesson 3: Implementing jQuery
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Bar Code Encoder In VS .NET Using Barcode encoder for ASP.NET Control to generate, create bar code image in ASP.NET applications. www.OnBarcode.comDecode Bar Code In Visual Basic .NET Using Barcode reader for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications. www.OnBarcode.com<script type="text/javascript"> $(document).ready(function () { $("#MainContent_ButtonSearch").click(function () { var empId = $("#MainContent_TextBoxEmpId").val(); $.ajax({ type: "POST", dataType: "json", contentType: "application/json", url: "EmployeeService.asmx/GetEmployee", data: "{'employeeId': '" + empId + "'}", success: function (data) { alert("Employee name: " + data.d); }, error: function () { alert("Error calling the web service."); } }); }); }); </script> Let s walk through this code. Note that the code is bound to the button click event when the page loads. Next, the user s input is assigned to a variable, empId. Then the call to $.ajax() is made. Notice that the settings are passed as name-value pairs separated by a colon. There is no set order to these pairs. The following list describes each setting:
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