Call JavaScript function from ASP.net code behind

Question

I’m trying to call a JavaScript function from Code behind but no luck so far. I tried to add the following snippets inside Page_Load method.

I’ve tried as below

ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "foo", "alert('test22222')", true);

Also as below

Page.ClientScript.RegisterStartupScript(Type.GetType("System.String"), "addScript", "alert('test22222');", true);

None worked for me. Is there anything I’m missing here? I would like to show the alert message before loading the page.

Any help appreciated. Thanks.

RegisterstartupScript will put the Javascript at the very end of the page, so the rendering will have completed (I think) before it's executed. You may better off just including the code in your ASPX page, somewhere near the top. — Tomas McGuinness
– Tomas McGuinness, Commented Apr 17, 2013 at 10:07

Guru Kara · Accepted Answer · 2013-04-17 09:57:29Z

2

You are missing a ; in you code. Try this it worked for me.

But i would suggest the ScriptManager.RegisterStartupScript over the Page.ClientScript.RegisterStartupScript as the first one is designed for AJAX calls. Which will work for even partial page post backs.

ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "foo", "alert('test22222');", true);

answered Apr 17, 2013 at 9:57

Guru Kara

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score 1 · Accepted Answer · 2013-04-17 10:50:54Z

1

you can implement it in page_prerender event

    protected void page_prerender( object sender, EventArgs e )
{
         your code here;
}

edited Apr 17, 2013 at 10:50

answered Apr 17, 2013 at 9:47

user1776054

2 Comments

MJM Over a year ago

This behaves same as the current one :(

MJM Over a year ago

I want to call a function before the page renders in the screen. So I tried to implement it. It didn't get called. I even called alert as given in the code that also didn't work.

Yeronimo · Accepted Answer · 2013-04-17 09:54:53Z

0

This will work. You forgot semicolon at end of your alert:

ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "foo", "alert('test22222');", true);

answered Apr 17, 2013 at 9:54

Yeronimo

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1 Comment

MJM Over a year ago

It has no effect :( same behavior

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