将 C# 中的 Javascript Keydown 事件添加到文本框

Question

I'm building a set of text boxes from asp.net repeater and trying to add a key down event from C# code to those text boxes to prevent user from entering a specific character ( comma(,) ). I can't use the text box id itself in Javascript because its built dynamically with diff id's. Now I have no idea how to pass the e object to the textbox's keydown event from C#.

Any suggestion is much appreciated.

Code Snippet :

 TextBox txtTextField = e.Item.FindControl("txtAns_1") as TextBox;
 txtTextField.Attributes.Add("keydown", "PreventChars(" + txtTextField +")");

Javascript

   function PreventChars(e) {

            var k = String.fromCharCode(e.which);

            if (k.match(/,/g))
            {
                e.preventDefault();
            }

        };

Answer 1

use ClientID

ClientID returns The control ID for HTML markup that is generated by ASP.NET.

Change Code Snippet to:

TextBox txtTextField = e.Item.FindControl("txtAns_1") as TextBox;
txtTextField.Attributes.Add("keydown", "PreventChars(" + txtTextField.ClientID +")");