Signum Function (all)

JavaScript performance comparison

Revision 2 of this test case created by Adam Hyland

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 : x === x ? 0 : NaN : NaN;
  }
  
  // 5. Simpler type-safe
  function sign5(x) {
    var check;
    check = typeof x === 'number' && x === x ? x : NaN;
    if (!check) {
      return check;
    } else {
      return x < 0 ? -1 : 1;
    }
  };

};
</script>

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
3. Artistic
test(sign3)
pending…
4. Safe
test(sign4)
pending…
2. Elegant
test(sign2)
pending…
1. Obvious
test(sign1)
pending…
1.1. Not So Obvious
test(sign1b)
pending…
5. Simpler Safe
test(sign5)
pending…

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Revisions

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