arguments.length vs. typeof param === 'undefined'

JavaScript performance comparison

Test case created by Ryan Grove

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    function checkLength(a, b) {
      return arguments.length > 1;
    }
   
    function checkType(a, b) {
      return typeof b !== 'undefined'
    }
};
</script>

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Testing in unknown unknown
Test Ops/sec
one arg [arguments.length]
window.result = checkLength('a');
pending…
one arg [typeof]
window.result = checkType('a');
pending…
two args [arguments.length]
window.result = checkLength('a', 'b');
pending…
two args [typeof]
window.result = checkType('a', 'b');
pending…

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