Info

This testcase compares the performance when checking if a variable (argument) is a function. typeof foo === 'function' vs. foo instanceof Function.

Preparation code

<script>
  var foo = function() {};
</script>

Test runner

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(function() {
 if (typeof foo === 'function') {}
}());

(function() {
 if (foo instanceof Function) {}
}());

(function() {
 if (typeof foo == 'function') {}
}());

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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 by Andreas Göbel on 21st March 2011
• Revision 2: published by Andreas Goebel on 21st March 2011
• Revision 3: published by Gildas on 21st March 2011
• Revision 4: published on 10th October 2012
• Revision 5: published on 26th April 2013
• Revision 6: published on 27th April 2013

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