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https://jsperf.com/negative-modulo/2
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https://jsperf.app/negative-modulo/2
Compare JS bit operation speed depending on whether the values are coming from a regular array or a typed array.
Expectations:
(1) TypedArray will be faster than raw array (since the engine can assume the value is 32-bits without checking)
(2) Raw arrays will take a performance hit for integers above 1e31 (since most engines can't use the small integer optimization on numbers that big)
(3) TypedArrays performance will not be affected by whether values are above 1e31 or not
Outcome: Both (2) and (3) seem correct across V8, SpiderMonkey, and JSC. However, (1) only seems to hold in Firefox (where typed array is twice as fast), as the raw array with small numbers performs slightly (10-20%) better on V8 and JSC.
COUNT = 1e6;
const makeRawArray = (offset) => {
const array = [];
for(i = 0; i<COUNT; i++) {
array.push(i + offset)
}
return array;
}
const ra1 = makeRawArray(0);
const ra2 = makeRawArray(0);
const ra1big = makeRawArray(1e31);
const ra2big = makeRawArray(1e31);
const makeTypedArray = (offset) => {
const array = new Uint32Array(COUNT);
for (i = 0; i<COUNT; i++) {
array[i] = i + offset;
}
return array;
}
const ta1 = makeTypedArray(0);
const ta2 = makeTypedArray(0);
const ta1big = makeTypedArray(1e31);
const ta2big = makeTypedArray(1e31);
Ready to run.
Test | Ops/sec | |
---|---|---|
Raw Array |
| ready |
Typed array |
| ready |
Raw Array (>1e31 ints) |
| ready |
Typed Array (>1e31 ints) |
| ready |
You can edit these tests or add more tests to this page by appending /edit to the URL.