Looping through values from c# array using javascript - Stack Overflow

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Okay, I've created an array in c# and want to access the values in a javascript for loop. Here's my global c# variables:

protected int count;
protected string[] arr = new string[20];

From there I add string values to the array in, let's say, the Page_Load() event.

And here's my ideal javascript code:

var count = <%= count %>;
for (var i = 0; i < count; i++) 
{
document.write(<%= arr[i] %>);
}

Now if I were to just use arr[0] that would pop up with the correct information for arr[0], so I know I've got that part right, but is there a way to use that javascript variable "i" inside the <%= %> tag?

Okay, I've created an array in c# and want to access the values in a javascript for loop. Here's my global c# variables:

protected int count;
protected string[] arr = new string[20];

From there I add string values to the array in, let's say, the Page_Load() event.

And here's my ideal javascript code:

var count = <%= count %>;
for (var i = 0; i < count; i++) 
{
document.write(<%= arr[i] %>);
}

Now if I were to just use arr[0] that would pop up with the correct information for arr[0], so I know I've got that part right, but is there a way to use that javascript variable "i" inside the <%= %> tag?

• c#
• javascript
• asp

Share Improve this question Follow asked Aug 23, 2011 at 0:29 Aaron VanderwielenAaron Vanderwielen 23733 silver badges1717 bronze badges

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4 Answers 4

Sorted by: Reset to default 5

The ASP.NET parts of the code execute on the server. JavaScript is executed in the browser. The server just sees the JavaScript as text, it is meaningless and non-functional. Only when the browser receives the page and interprets the JS is it executed.

Remember, the server and the client PC are two different systems connected by a network. If you want to process data from system A on system B, you need to send the data to B.

If you want to send the data in the array to the browser so it can use it in some JavaScript, you need to serialize the array.

Something like this:

var myArray = <% = new JavaScriptSerializer().Serialize(serverSideArray) %>;
for(var i = 0; i < myArray.length; i++) {
    document.write(myArray[i]);
}

Hope it is useful to you... It was run fine in my test

    <script language ="javascript">
        var count = <%= count %>;
        alert(count);

        <%
           for(int i=0;i<count;i++){
         %>
            document.write(<%= arr[i] %>);
        <%}%>

    </script>

Sadly, I don't think so; because the Javascript is evaluated at run-time in the browser, but the server block is evaluated at pile time on the server.

You can probably just expand the scope of your server block and just loop through arr in C#

I am going to get flamed for this, but here goes:

Server-side:

protected void Page_Load(object sender, EventArgs e)
{
    string[] arr = new string[] { "1", "2", "3" };

    StringArr = string.Join(",", arr.Select(a => string.Format("\"{0}\"", a)).ToArray());
}

protected string StringArr;

Client-side:

<script language="javascript" type="text/javascript">
    var arr = [<%=StringArr %>];

    alert(arr.length);
</script>

Let the ridicule begin.

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