ASP.Net textbox onblur event

Question

Hi, I have a textbox, whose values I need to validate (if value of textbox is 50, then display message in lblShowMsg) when the user tabs out of the textbox (onBlur event). I can't seem to get the syntax right.

I have this code on my pageload event:

protected void Page_Load(object sender, EventArgs e)
{
    txtCategory.Attributes.Add("onblur", "validate()"); 

}

But I can't seem to get the javascript code correct. Any suggestions?

Answer 1

Is that the actual code in your Page_Load? You need to use the name of the control, and not the type name for TextBox. For example, you may want to try:

 textBox1.Attributes.Add("onblur", "validate();");

where "textBox1" is the ID you assigned to the textBox in your markup instead.

Also, from Javascript, it's very possible that the ID of the textBox has changed once it gets rendered to the page. It would be better if you would pass the control to the validate function:

function validate(_this)
{
    if (_this.value == "50")
        // then set the ID of the label.  
}

Then you would set the attribute like this:

textBox1.Attributes.Add("onblur", "validate(this);");

Lastly, I would strongly recommend using the JQuery library if you're doing anything in Javascript. It will make your life 10x easier.

Answer 2

This works.

Textbox1.Attributes.Add("onblur","javascript:alert('aaa');");

Make sure that functiion lies in the script part of the page.

---

My page

<script type="text/javascript">
    function Validate() {

        alert('validate');

    }

</script>

---

code behind

public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Textbox1.Attributes.Add("onblur","Validate();"); } }