Discussion on:

Accessing form data via JavaScript and the DOM

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In Listing A, where you test for fullname not null and value equal to spaces, should the else cause flag to be set to true rather than false? Same question for contactnumber.

Yes. In addition to these basic syntax errors...

varfullname =
varcontactnumber =

...which should be:

var fullname =
var contactnumber =

IE is broken in that it allows indices to use parentheses ().

Changing it to brackets lets this work in standard compliant browsers - so change the <nclick event to this -

<nclick="document.getElementsByTagName('p')[0].innerHTML = document.getElementById('fullNameField').value;"

I just changed the line that sets the variable to use brackets. So now you have:

var contactnumber = document.getElementsByName("contactNumber")[0];

Code runs fine in Firefox and IE after that.