Signum Function (all)

JavaScript performance comparison

Revision 6 of this test case created by Joshua

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) {
      sign(1) // +1
      sign(1908235) // +1
      sign(-.1e-1) // -1
      sign(Math.random() * 2 - 1) // ??
      sign(0) //  0
      sign(0.00000) //  0
      sign(+Infinity) // +1
      sign(-Infinity) // -1
      sign(NaN) //  0 or NaN
   
      // other types
      sign("0")
      sign("")
      sign([])
      sign("+23")
      sign(null)
      sign(undefined)
    }
   
   
    // 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. Type-safe:
   
    function sign4(x) {
      return typeof x == 'number' ? x ? x < 0 ? -1 : 1 : isNaN(x) ? NaN : 0 : NaN;
    }
   
    function sign5(x) {
      return typeof x === 'number' ? x ? x < 0 ? -1 : 1 : x === x ? 0 : NaN : NaN;
    }
};
</script>

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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)
pending…
3. Artistic
test(sign3)
pending…
4. Safe
test(sign4)
pending…
5. magic
test(sign5)
pending…

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