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I was working on an application which used AJAX and needed the XMLHttpRequest object to communicate with an ASP.NET Generic Handler (.ashx), which contained some server-side logic. Here’s a working prototype if you have a similar requirement
We will first create an ASP.NET handler (ashx) which accepts a ‘Name’ parameter and greets the user by appending ‘Hello’ to it.
We will then call this ASP.NET Handler (ashx) via JavaScript by passing in a value entered in an ASP.NET TextBox.
ASP.NET Handler
Right click your ASP.NET Project > Add New Item > Generic Handler > call it SayHello.ashx. Add the following code:
<%@ WebHandler Language="C#" Class="SayHello" %>
using System;
using System.Web;
public class SayHello : IHttpHandler {
public void ProcessRequest (HttpContext context) {
context.Response.ContentType = "text/plain";
string param = context.Request.Params["Name"];
context.Response.Write("Hello, " + param);
}
public bool IsReusable {
get {
return false;
}
}
}
JavaScript Code
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Call ASHX in JavaScript by DevCurry.com</title>
<script type="text/javascript">
var httpReq = null;
function callASHX() {
httpReq = XMLHttpRequest();
httpReq.onreadystatechange = XMLHttpRequestCompleted;
httpReq.open("GET", "SayHello.ashx?Name=" +
document.getElementById('<%=txtName.ClientID%>').value, true);
httpReq.send(null);
}
// initialize XMLHttpRequest object
function XMLHttpRequest() {
var xmlHttp;
try {
// Opera 8.0+, Firefox, Safari
xmlHttp = new XMLHttpRequest();
}
catch (e) {
// IEBrowsers
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e) {
return false;
}
}
}
return xmlHttp;
}
function XMLHttpRequestCompleted()
{
if (httpReq.readyState == 4)
{
try
{
alert(httpReq.responseText);
}
catch (e)
{
}
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<asp:Button ID="btnCall" runat="server" Text="Enter Text and Click"
OnClientClick="callASHX();"/>
</div>
</form>
</body>
</html>
In the code shown above, on the asp.net button click event, we call the callASHX() javascript function. In this function, we first initialize our XMLHttpRequest object by calling the XMLHttpRequest() function and asynchronously invoke an .ashx file called SayHello.ashx and pass the textbox value to it. If the request to the .ashx handler completes successfully, the XMLHttpRequestCompleted() function is invoked and the user is greeted.
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comments
5 Responses to "Call ASP.NET Handler (ASHX) using JavaScript"try using jquery??
Is this book available in print?
@niku: jQuery? Why? :)
@Jonathan Wood: Are you referring to this book - http://www.dotnetcurry.com/order/jQueryASPNETRecipesBook.aspx ? There is only an ebook version available.
Because with jquery you need much less code
isn't it necessary to register the httphandler in web.config????
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