Question

I have a form with one textbox and one button. Here I need to validate if users are not entering invalid data in the textbox so I have a function in site.masters “head” which is called “onclick” event. But I get an error:

“Microsoft JScript runtime error: ‘document.Form1.studentID’ is null
or not an object”

Here “Form1” is the “id” of the form

Here is my javascript code from Site.Master:

<script language="javascript">

    function verifyInput() {
        if (document.Form1.studentID.value != "testID") 
      {
            alert("please enter valid student ID")
      }
    }

</script>

Here is my form code from my view:

<form id="Form1" method="get" action="/AddStudent/" runat="server">
    <label for="id">
        <br /><br /> Student ID:
    </label>
        <input type="text" name="studentID" maxlength=10/>
        <input type="submit" value="Add Student" onclick="verifyInput()"/>
</form>

Answer 1

I believe it needs to be

document.forms.Form1.studentId.value

but really you should be using document.getElementById()

edit: as stated in the answer, yes it should be a name, not an ID, unless you use document.getElementById instead of the old fashioned dot notation