Question

I get this javascript error message

Error: a.getAttribute("rel") is null

on these lines of code

  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") && !a.disabled) return a.getAttribute("title");
  }
  return null;

any ideas how do I sort it out?

Thanks.

Answer 1

Before using a.getAttribute("rel") like you are doing :

if(a.getAttribute("rel").indexOf("style") != -1 && 
    a.getAttribute("title") && 
    !a.disabled) {
    return a.getAttribute("title");
}

You should test if it’s not null (or not “falsy”) :

if(a.getAttribute("rel") &&
    a.getAttribute("rel").indexOf("style") != -1 && 
    a.getAttribute("title") && 
    !a.disabled) {
    return a.getAttribute("title");
}

With the first portion of condition I added at the beginning of the if expression, the second (and the ones after) portion of the condition will be evaluated only if a.getAttribute("rel") is truthy — i.e. the won’t be evaluated when a.getAttribute("rel") is null.