如何从后台代码执行javascript函数，但仅在页面加载后执行

Question

I've found other solution on how to executes a javascript function from code-behind. The problem is that it firing before the page loads, so I can't add logic to it.

if(result)
{
   Page.ClientScript.RegisterClientScriptBlock(typeof(Page), 
                                               "Script", "confirmPwdChange();", true);
}

On the client side

<script>
   confirmPwdChange()
   {
     alert("Password has been successfully changed.");
     //Add more logic here, after user clicks the OK button...
   }
</script>

No Jquery, if possible.

Thanks for helping.

Answer 1

I think you're looking for PageRequestManager

List of PageRequestManager events

var prm = Sys.WebForms.PageRequestManager.getInstance();

// beginRequest: before postback to server
prm.add_beginRequest(BeginRequestHandler);

// endRequest: after postback to server
prm.add_endRequest(EndRequestHandler);

function BeginRequestHandler(sender, args) {
    // do stuff
}

function EndRequestHandler(sender, args) {
    // do stuff
}

Answer 2

You might want to include the window.onload in your script file. something like this..

StringBuilder script = new StringBuilder();
script.Append("var existingHandler = window.onload;");
script.Append("window.document.body.onload = function(){ confirmPwdChange(); if (existingHandler){ existingHandler()}}");
Page.ClientScript.RegisterClientScriptBlock(typeof(Page), 
                                           "Script", script.ToString(), true);

this ensure, your change password is called on page load and retains any other existing handlers declared already on the page.