CODEWITHSUNDEEP
c#javascriptasp.net
Avinash Chandra
Avinash Chandra

Reputation: 183

calling javascript function from code behind

I am trying to call a javascript function from code behind on the button click event. below is my javascript code.

  ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "strScript", "javascript:clearBox();", true);

and the function is

<script type="text/javascript">

function clearBox() {


    alert("Test");

}
</script>

I get an error "Object expected"

Upvotes: 0

Views: 1580

Answers (2)

Viktor S.
Viktor S.

Reputation: 12815

You should use OnClientClick property of a button:

<asp:Button runat="server" OnClientClick="clearBox()" />

RegisterClientScriptBlock will only place a piece of code on a page:

<script type="text/javascript">
      javascript:clearBox();
</script>

And this will not work as it is not a valid code (because of javascript: which is used for anchors to run js from href: <a href="javascript:some_code_here()"></a>)

Another option, if you want RegisterClientScriptBlock is to use addEventListener to assign onclick handler to your button. Here is code snippet for this (cross browser and pure JS). It may be used like this:

  ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "strScript", "addListener('"+button.ClientID+"', 'click', clearBox);", true);

But it is better to replace RegisterClientScriptBlock with [RegisterStartupScript](http://msdn.microsoft.com/en-us/library/z9h4dk8y.aspx) where first one may be called before all HTML is loaded and there may be no button yet.

Upd Well, thanks to hvd. He reminded me that there are labels in JS and actually javascript:clearBox() is a valid code, but it will not do what OP wants

Upvotes: 4

Pouya
Pouya

Reputation: 1918

Use this code:

Page.ClientScript.RegisterStartupScript(this.GetType(),  "Error", "clearBox();", true);

Upvotes: 0

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