当 javascript function 添加到 web 页面时，ASP.Net OnTextChanged 事件不会触发

Question

I have a TextBox on an ASP.Net page with OnTextChanged set to a code-behind function:

<asp:TextBox ID="txtFirstName" runat="server" Width="150px"
    OnTextChanged="txtFirstName_TextChanged" AutoPostBack="true"></asp:TextBox>

protected void txtFirstName_TextChanged(object sender, EventArgs e)
{
    if (cbExisting.Checked)
    {
        DataSet ds = 
            DataGateway.getExistingEmployeeInfo(txtLastName.Text, txtFirstName.Text);
        if (ds != null && ds.Tables[0].Rows.Count > 0)
        {
            if (ds.Tables[0].Rows.Count == 1)
                txtEmployeeID.Text = ds.Tables[0].Rows[0]["EmployeeID"].ToString();
            else
            {
                lblError.Text = "There is more than one existing employee with that name.<br>";
                lblError.Text = lblError.Text + "Please indicate which employee you want.<br>";
                foreach (DataRow drow in ds.Tables[0].Rows)
                {
                    TableRow trow = new TableRow();
                    TableCell cell = new TableCell();
                    CheckBox cb = new CheckBox();
                    cb.Text = drow["FirstName"].ToString() + " " + 
                        drow["LastName"].ToString() + " (" + 
                        drow["EmployeeID"].ToString() + ")";
                    cb.AutoPostBack = true;
                    cb.EnableViewState = true;
                    cb.ViewStateMode = ViewStateMode.Enabled;
                    cb.Attributes.Add("onclick", "populateEmpID('"+ 
                        cb.ClientID + "','" + 
                        txtEmployeeID.ClientID + "');");
                    cell.Controls.Add(cb);
                    trow.Cells.Add(cell);
                    tblMultEmps.Rows.Add(trow);
                }
            }
        }
    }
}

This all works just fine UNTIL I add the javascript function referred to in my code to the web page:

function populateEmpID(CheckBoxID, EmployeeID) {
        var cb = document.getElementById(CheckBoxID);
        var tbempid = document.getElementById(EmployeeID);
        int cblen = cb.length;
        String empid = cb.value.substring(cblen - 6, cblen - 1);
        tbempid.value = empid;
    }

Once I add this javascript function, the OnTextChanged event stops firing.

Note that the TextBox is in an HTML table within an ASP.Net View control. Also, there are a multitude of javascript functions on this page that work fine. This issue only arises when I try to add the function above. The project is using.Net Framework 4, and I'm working in Visual Studio 2017. What the heck is going on here?

Answer 1

This might not solve the entire problem but these statements are not valid js:

int cblen = cb.length;
String empid = cb.value.substring(cblen - 6, cblen - 1);

Should be

var cblen = cb.length;
var empid = cb.value.substring(cblen - 6, cblen - 1);

Again, there could be other issues.