Question

I’m getting a

Breaking on JScript runtime error - Unknown runtime error 

on this line:

c.innerHTML= '<a name="a1" class="b" href="' + d[2].value + '">' + 
              d[1].value + '</a>';

Answer 1

I noticed that c is an anchor element and you are trying to set its innerHTML to create a child anchor element, which is not valid HTML, though most browsers can tolerate invalid HTML. Something that would make things clearer and help you identify the problem would be to write your code as follows:

var b = document.getElementById('Bb1c');
var c = document.createElement('a');
var d = document.forms['f3'].elements;
c.name = 'a1';
c.className = 'b';
c.href = d[2].value;
var value = d[1].value;
// You should really HTML-escape value before assigning it.
c.innerHTML = value;
b.appendChild(c);

This will likely still have the same error as before, but it should be easier to figure out on which line the error is occurring. For example, the problem could be that either d[1] or d[2] is null.