Run results for: JS number to UInt8Array 64-bit little endian 2

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36

Browser: Chrome 111

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Through DataView	2155226.0 Ops/sec
Direct	7982841.0 Ops/sec
With BigInt	982669.6 Ops/sec
Simple Loop	7913822.0 Ops/sec
Loop No Assignment	7869216.0 Ops/sec
Loop No Assignment No Second Counter	7947381.0 Ops/sec
Loop Exit on 0	8076628.0 Ops/sec
Loop Exit on 0 single byte	8140287.0 Ops/sec
Loop Exit on 0 with 0	8233825.0 Ops/sec

Script Preparation code:

function numberToUint8Array64LE_DataView(num) {
    const buf = new ArrayBuffer(8)
    const view = new DataView(buf)
    view.setUint32(0, num, true)
    view.setUint32(4, num >>> 32, true)
    return new Uint8Array(buf)
}

function numberToUint8Array64LE_direct(num) {
    const result = new Uint8Array(8)
    result[0] = num & 0xff
    result[1] = (num >>> 8) & 0xff
    result[2] = (num >>> 16) & 0xff
    result[3] = (num >>> 24) & 0xff
    result[4] = (num >>> 32) & 0xff
    result[5] = (num >>> 40) & 0xff
    result[6] = (num >>> 48) & 0xff
    result[7] = (num >>> 56) & 0xff
    return result
}

function numberToUint8Array64LE_bigint(num) {
    const bigIntValue = BigInt.asUintN(64, BigInt(num));
    const buffer = new ArrayBuffer(8);
    const dataView = new DataView(buffer);
    dataView.setBigUint64(0, bigIntValue, true);
    return Uint8Array.from(buffer.slice(0, 8));
}

function numberToUint8Array64LE_withLoop(num) {
    const result = new Uint8Array(8)
    for (let i = 0; i < 8; i++) {
        result[i] = num & 0xff
        num = num >>> 8
    }
    return result
}

function numberToUint8Array64LE_withLoop_noAssignment(num) {
    const result = new Uint8Array(8)
    result[0] = num & 0xff
    for (let i = 1, j = 8; i < 8; i++, j += 8) {
        result[i] = (num >>> j) & 0xff
    }
    return result
}

function numberToUint8Array64LE_withLoop_noAssignment_noSecondCounter(num) {
    const result = new Uint8Array(8)
    result[0] = num & 0xff
    for (let i = 1; i < 8; i++) {
        result[i] = (num >>> (i << 3)) & 0xff
    }
    return result
}

function numberToUint8Array64LE_withLoop_bugoutOn0(num) {
    const result = new Uint8Array(8)
    for (let i = 0; num != 0; i++, num = num >>> 8) {
        result[i] = num & 0xff
    }
    return result
}

Tests:

Through DataView
numberToUint8Array64LE_DataView(0xababababab)
Direct
numberToUint8Array64LE_direct(0xababababab)
With BigInt
numberToUint8Array64LE_bigint(0xababababab)
Simple Loop
numberToUint8Array64LE_withLoop(0xababababab)
Loop No Assignment
numberToUint8Array64LE_withLoop_noAssignment(0xababababab)
Loop No Assignment No Second Counter
numberToUint8Array64LE_withLoop_noAssignment_noSecondCounter(0xababababab)
Loop Exit on 0
numberToUint8Array64LE_withLoop_bugoutOn0(0xababababab)
Loop Exit on 0 single byte
numberToUint8Array64LE_withLoop_bugoutOn0(0xab)
Loop Exit on 0 with 0
numberToUint8Array64LE_withLoop_bugoutOn0(0)

Run results for: JS number to UInt8Array 64-bit little endian 2

Through DataView

Direct

With BigInt

Simple Loop

Loop No Assignment

Loop No Assignment No Second Counter

Loop Exit on 0

Loop Exit on 0 single byte

Loop Exit on 0 with 0