typeof vs. tostring to check function type

JavaScript performance comparison

Revision 2 of this test case created

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var a=function(){};
    var f=function(x){return typeof x==="function";};
};
</script>

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Testing in unknown unknown
Test Ops/sec
typeof
typeof a==="function"
pending…
tostring
Object.prototype.toString.call(a) === "[object Function]";
 
pending…
duck-typing
!!(a && a.constructor && a.call && a.apply);
 
pending…
typeof as function
f(a)
pending…

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