Signum Function (all)

JavaScript performance comparison

Revision 9 of this test case created

Info

Derived from this question on StackOverflow: Number.sign() in JavaScript

Versions of the test: test everythingonly numbersonly integers

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Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    // OUR TEST CODE (see other versions)
    function test(sign) {
      var agg = 0;
      for (var i=0; i<10000; i++) {
        agg += sign(Math.random()*2-1);
      }
    }
   
   
    // 1. Obvious and fast
    function sign1 (x) { return x > 0 ? 1 : x < 0 ? -1 : 0; }
   
    // 1.1 Modification from kbec - one type cast less, more performant, shorter
    function sign1b(x) { return x ? x < 0 ? -1 : 1 : 0; }
   
    // 2. Elegant, short, not so fast
    function sign2 (x) { return (+x) && (+x) / Math.abs(+x); }
    // (some issues with several cases, see answer.)
   
    // 3. The art... but very slow
    function sign3 (x) { return (x > 0) - (x < 0); }
   
    // 4. Using bit-shift
    function sign4(x) { return (x >> 31) + (x > 0 ? 1 : 0); }
   
    // 5. Type-safe:
    function sign5 (x) {
            return typeof x === 'number' ? x ? x < 0 ? -1 : 1 : x === x ? 0 : NaN : NaN;
    }
   
    // 6. Math.sign
    function sign6(x){
       return Math.sign(x);
    }
   
    // 7. Type-safe fast:
    function sign7 (x) {
       x = +x;
       return x ? x < 0 ? -1 : 1 : 0;
    }
};
</script>

Test runner

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Testing in unknown unknown
Test Ops/sec
1. Obvious
test(sign1)
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1.1. Not So Obvious
test(sign1b)
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2. Elegant
test(sign2)
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3. Artistic
test(sign3)
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4. Bit-shift
test(sign4)
pending…
5. Safe
test(sign5)
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6. Math.sign
test(sign6)
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7. Safe fast
test(sign7)
pending…

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