This repository is a microbenchmark that measures speed of various iteration approaches in javascript.
We measured the following approaches:
// Option 1: regular forEach
array.forEach(cb);
// Option 2: Plain for loop:
for (let i = 0; i < array.length; ++i) cb(array[i])
// Option 3: for .. of loop:
for (let v of array) cb(v)
// Option 4: over iterator:
let iterator = array[Symbol.iterator]();
for (let v of iterator) cb(v);
// Option 4: yield* operator:
yield *array;The benchmark initializes 10,000 vectors vectors, and then computes a square sum of the x dimension
for(let v of vectors) {
sum += v.x * v.x
}Running in node v16.4.0
array.forEach(cb) x 6,751 ops/sec ±7.00% (81 runs sampled)
for (let i = 0; i < array.length; ++i) cb(array[i]) x 8,820 ops/sec ±4.04% (83 runs sampled)
for (let item of array) cb(item) x 8,322 ops/sec ±3.79% (86 runs sampled)
iterator x 4,147 ops/sec ±1.66% (85 runs sampled)
yield * x 2,228 ops/sec ±1.57% (88 runs sampled)
Fastest is for (let i = 0; i < array.length; ++i) cb(array[i]),array.forEach(cb)
We also performed the same set of tests with a Set object. Obviously, we couldn't do plain old
for loop, but the rest of the approaches are still applicable.
node setIterators.js
Running in node v16.4.0
set.forEach(cb) x 5,545 ops/sec ±2.04% (86 runs sampled)
for (let item of set) cb(item) x 8,019 ops/sec ±4.93% (83 runs sampled)
iterator x 5,580 ops/sec ±12.76% (68 runs sampled)
yield * x 2,063 ops/sec ±6.32% (82 runs sampled)
Fastest is for (let item of set) cb(item)
» node mapIterators.js
Running in node v16.4.0
map.forEach(cb) x 5,135 ops/sec ±2.69% (86 runs sampled)
for (let item of map) cb(item) x 5,486 ops/sec ±3.41% (83 runs sampled)
iterator x 4,904 ops/sec ±1.97% (84 runs sampled)
yield * x 1,962 ops/sec ±1.49% (88 runs sampled)
entriesForOfLoop x 5,855 ops/sec ±1.62% (87 runs sampled)
entriesForOfLoopKV x 4,040 ops/sec ±3.32% (84 runs sampled)
valuesForOfLoop x 8,280 ops/sec ±3.37% (84 runs sampled)
Fastest is valuesForOfLoop
If you want to add other tests - please do so. Pull requests are very much welcomed!
- Array vs Object - what is faster: store array of vectors, or encode vectors into array?
- Set vs Object - what is faster: use object fields or Map/Set collections?
MIT