ASP.net - What is the best way to pass a list from code behind to java script?

Question

In javascript, I want to compare the selected value from a dropdown list to a list of values from my C# code behind. I've tried passing a string list through a HiddenField, but I can't get past the problem of 'Unable to get property 'split' of undefined or null reference'.

Looking around Stackoverflow and elsewhere I've tried many variations of the following code but the 'split error' has me stymied.

<asp:HiddenField ID="HiddenFieldList" runat="server" />

//Code behind:
HiddenFieldList.Value = String.Join(",", ValuesList);

//javascript
var CSVList = document.getElementById("HiddenFieldList").value;
var HFList = [];
HFList = this.CSVList.split(',');

// hoping to get to here...
for(i = 0; i < HFList.length; i++) 
{
   if (DDL == HFList[i])
   {
       do stuff ;
       break ;
    }
 }

Or...instead of assigning a string list to my hidden field should I pass an array?? Fwiw - the project is not MVC.

Edit: My code behind list is derived from values in a datatable column.

On your ASP.NET page, at the server side, just generate a bunch of text that begins with <script> ends with </script> and has var theArray = [...]' inside. At the client side you'll end up with theArray as a local variable. — Wiktor Zychla
– Wiktor Zychla, Commented Jun 7, 2018 at 14:00
Change your code this.CSVList.split(‘,’) to CSVList.split just remove this. — Mohsin Mehmood
– Mohsin Mehmood, Commented Jun 7, 2018 at 15:01

Mohsin Mehmood · Accepted Answer · 2018-06-07 15:05:51Z

2

Change the following line of code

HFList = this.CSVList.split(',');

to

HFList = CSVList.split(',');

because CSVList is local variable.

answered Jun 7, 2018 at 15:05

Mohsin Mehmood

4,2662 gold badges15 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

JonV Over a year ago

It now works as expected. What is frustrating is that I'd previously tried the same text as you suggested - and still received the error. Thank you for your time.

Collectives™ on Stack Overflow

ASP.net - What is the best way to pass a list from code behind to java script?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related