Info

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

Preparation code

<script>
  var u, 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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if (u === undefined) {
 e = '';
}

if (u == undefined) {
 e = '';
}

if (typeof u === 'undefined') {
 e = '';
}

if (typeof u == 'undefined') {
 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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