Pass List<int> as argument of Javascript function

Question

I want to accept List as argument of javascript function.
I am calling this function from code behind.
And passing one List to the function.
But i got "System.Collections.Generic.List`1[System.Int32]" as value of argument when function called.
What should i do to get list when function called.
My code is:
Default.aspx.cs

protected void Page_Load(object sender, EventArgs e)
    {
        List<int> num = new List<int> { 12, 13, 14, 15, 16, 17, 18 };
        List<int> oddNum = num.Where(n => n % 2 == 1).ToList();

        ScriptManager.RegisterStartupScript(this, GetType(), "test", "test('"+oddNum+"');", true);  
    }

Default.aspx

<head runat="server">
    <title></title>
    <script type="text/javascript">

        function test(oddNum) {
            alert(oddNum);
        }
    </script>
</head>

Carlos SS · Accepted Answer · 2016-06-02 18:30:39Z

2

Two issues:

You're relying on List<int>#ToString, which will give you a string like "System.Collections.Generic.List`1[System.Int32]". You need to do something to output the list usefully.
You're passing it to your JavaScript function as a string. While that can work (we could convert it to an array in JavaScript), there's no need; you can pass it directly as an array.

On the server, convert the list to a string using string.Join and use [ and ] instead of ' around it:

ScriptManager.RegisterStartupScript(this, GetType(), "test", "test([" + string.Join(",",oddNum) + "]);", true);

Say our list has 1, 3, and 5 in it. That calls your function like this:

test([1, 3, 5]);

Your JavaScript function then receives an array:

function test(oddNum) {
    // Use the oddNum array
}

edited Jun 2, 2016 at 18:30

Carlos SS

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answered Mar 16, 2015 at 9:45

T.J. Crowder

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1 Comment

Trusha Savsani Over a year ago

Ya its useful.. I got the result without manually separate result by ','. Thanks.

Yannick Meeus · Accepted Answer · 2015-03-16 09:41:16Z

1

Try the following:

ScriptManager.RegisterStartupScript(this, GetType(), "test", "test('" + string.Join(",", oddNum) + "');", true);

The String.Join(...) method will take in a delimiter (in this case it's ,) and a List, it will then concatenate every element in the list, separating them using the delimiter.

answered Mar 16, 2015 at 9:41

Yannick Meeus

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1 Comment

Trusha Savsani Over a year ago

Thanks... I got the result.

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