Marks field validation

I want numeric javascript validation for marks field. Marks entered should be out of 5 means user can enter upto 5 marks not more than that. marks may be in decimal like 4.25 after decimal there should be 2 digits can any one help me..

My text box is inside the data grid so on item data bound iam doing coding like If e.Item.ItemType = ListItemType.Alt开发者_开发知识库ernatingItem Or e.Item.ItemType = ListItemType.Item Then

        TxtMarks = CType(e.Item.FindControl("TxtMarks"), TextBox)

       TxtMarks.Attributes.Add("onkeypress", "javascript:return validateMark()")


    End If

but iam not getting proper code to validate my requirement.

  TxtMarks = CType(e.Item.FindControl("TxtMarks"), TextBox)

   TxtMarks.Attributes.Add("onkeypress", "return validateMark()")


End If

Try this.

You should be delete javascript: in onkeypress value

function validateMark(e) {
    var value = e.target.value;
    value = parseFloat(value.substring(0, 4));
    if (isNaN(value)) {
        return false;
    }
    if (value < 0 || value > 5) {
        return false;
    }

    return true;
}