Creation & call times for different binding techniques

bench-james-both.js

// Micro-benchmark to answer the question in https://twitter.com/thejameskyle/status/905403367949647874

if (typeof console === 'undefined') console = {log:print};

var closuresOriginal = (function() {
  const outer = a => {
    const inner = b => a + b;
    return inner(2);
  };

  return function closuresOriginal(a) {
    return outer(a);
  }
});

const inner1 = (a, b) => a + b;
var closuresInitialTransformHoisted = (function() {

  const outer = a => inner1(a, 2);

  return function closuresInitialTransformHoisted(a) {
    return outer(a);
  }
});

var closuresInitialTransform = (function() {
  const inner = (a, b) => a + b;
  const outer = a => inner(a, 2);

  return function closuresInitialTransform(a) {
    return outer(a);
  }
});

var closuresSymbolTransform = (function() {
  const _a = Symbol('a');
  const inner = b => inner[_a] + b;
  const outer = a => {
    inner[_a] = a;
    return inner(2);
  };

  return function closuresSymbolTransform(a) {
    return outer(a);
  }
});

var closuresBind = (function() {
  const inner = (a, b) => a + b;
  const outer = inner.bind(undefined, 2);

  return function closuresBind(a) {
    return outer(a);
  }
});

const inner2 = (a, b) => a + b;
var closuresBindHoisted = (function() {

  const outer = inner2.bind(undefined, 2);

  return function closuresBindHoisted(a) {
    return outer(a);
  }
});


var TESTS = [
  closuresOriginal,
  closuresInitialTransform,
  closuresInitialTransformHoisted,
  closuresSymbolTransform,
  closuresBind,
  closuresBindHoisted,
];
var a = 40;

var n = 2e7;

function test(fn) {
  var result;
  for (var i = 0; i < n; ++i) result = fn(a);
  return result;
}

console.log('--- Create');

for (var j = 0; j < TESTS.length; ++j) {
  test(TESTS[j]);
}

for (var j = 0; j < TESTS.length; ++j) {
  var startTime = Date.now();
  test(TESTS[j]);
  console.log('Create ' + TESTS[j].name + ' : ', (Date.now() - startTime), 'ms.');
}


console.log('--- Call');

for (var j = 0; j < TESTS.length; ++j) {
  test(TESTS[j]());
}

for (var j = 0; j < TESTS.length; ++j) {
  var startTime = Date.now();
  test(TESTS[j]());
  console.log('Call ' + TESTS[j].name + ' : ', (Date.now() - startTime), 'ms.');
}

Output from d8 on V8 master branch on MacBook.

--- Create
Create closuresOriginal : 664 ms.
Create closuresInitialTransform : 910 ms.
Create closuresInitialTransformHoisted : 669 ms.
Create closuresSymbolTransform : 2235 ms.
Create closuresBind : 1165 ms.
Create closuresBindHoisted : 677 ms.
--- Call
Call closuresOriginal : 308 ms.
Call closuresInitialTransform : 368 ms.
Call closuresInitialTransformHoisted : 248 ms.
Call closuresSymbolTransform : 788 ms.
Call closuresBind : 358 ms.
Call closuresBindHoisted : 372 ms.