从CodeBehind文件中调用JS函数

Question

I am having trouble accessing a Javascript function from my code behind file. I need to do this as I am using the GoogleMaps JS API to add markers to a map based on addresses retrieved from my database. I have a function called AddMarker that takes in the address as a parameter, so I need to be able to call that from my code behind file in the page_load function.

To simplify the question, how I can I call this javascript function to display an alert with a string passed from my code behind file?:

function hello(message)
{
alert(message)
}

Thanks in advance!

PS Either vb or c# will do :)

Answer 1

That should do:

 protected void Page_Load(object sender, EventArgs e) 
 { 
     string bing = "link";
     Response.Write(@"<script language='javascript'>alert(bing);</script>");
 }

Answer 2

I'm not certain if this is best practice, but you could just render out a call to the JS function somewhere in your page, after it has been defined.

Or you could use jQuery to delay the call until everything in the page is rendered.

So

<script type="text/javascript">

$(document).ready(function(){

hello("myAspString");

});

</script>

Replace myAspString with your content, making sure to preserve the quotes as needed by JS.

Answer 3

This code will cause the function hello to be called with value from the code behind:

string value = "world";
Page.ClientScript.RegisterClientScriptBlock(this.Page.GetType(), "my_script", string.Format("hello('{0}');", value.Replace("'", "\\'")), true);

The RegisterClientScriptBlock will append proper <script> tags to the HTML output sent to browser and inject your code in there.

The second argument is the "key" of the script, it enable you to have several statements and check if you already registered specific statement based on the key. The last argument tells the framework to add <script> tags for you.

You need to replace any single quotes with the proper escape sequence to avoid breaking the string when it contains single quotes as this is the "delimeter" used to pass the value to the function.

Answer 4

You may consider this a hack but you could always put your message in an html element like:

<p id='message' style='display: none;'>Your Message</p>

Then in your javascript:

function hello()
{
    var m = document.getElementById('message').innerHTML;
    alert(m);
}