Info

Check performance of === vs == in varying situations.

Preparation code

<script>
  var u, n = null,
      e = '',
      isU = function(v) {
      return typeof v === 'undefined';
      },
      isN = function(v) {
      return v === null;
      },
      isUN = function(v) {
      return typeof v !== 'undefined' && v !== null;
      },
      isUNfn = function(v) {
      return !isU(v) && !isN(v);
      },
      isUNb = function(v) {
      return !!!v;
      };
</script>

Test runner

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Java applet disabled.

if (n === null) {
  e = '';
}

if (n == null) {
  e = '';
}

if (isU(n)) {
  e = '';
}

if (isN(n)) {
  e = '';
}

if (isUN(n)) {
  e = '';
}

if (isUNfn(n)) {
  e = '';
}

if (isUNb(n)) {
  e = '';
}

if (n) {
  e = '';
}

if (!n) {
  e = '';
}

if ( !! n) {
  e = '';
}

if ( !! !n) {
  e = '';
}

if (u === null) {
  e = '';
}

if (u == null) {
  e = '';
}

if (isU(u)) {
  e = '';
}

if (isN(u)) {
  e = '';
}

if (isUN(u)) {
  e = '';
}

if (isUNfn(u)) {
  e = '';
}

if (isUNb(u)) {
  e = '';
}

if (u) {
  e = '';
}

if (!u) {
e = '';
}

if ( !! u) {
  e = '';
}

if ( !! !u) {
  e = '';
}

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Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:

• Revision 1: published on 3rd June 2011
• Revision 2: published on 3rd June 2011
• Revision 3: published by Mike McCaughan on 6th July 2011
• Revision 4: published by Mike McCaughan on 13th October 2011
• Revision 5: published by Mike McCaughan on 13th October 2011
• Revision 6: published by Mike McCaughan on 13th October 2011
• Revision 7: published by Mike McCaughan on 6th December 2011
• Revision 8: published on 22nd March 2013

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