Info

Check undefined: typeof vs. string coercion vs. toString prototype

Preparation code

 
<script>
  Benchmark.prototype.setup = function() {
    var toString = Object.prototype.toString;
  };
</script>

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(typeof (void 0) === "undefined");

((void 0) + "" === "undefined");

(toString.call(void 0) === "[object Undefined]");

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