Question

我相信，现在，像V8这样的JavaScript引擎始终能够检测到数组只有0-255范围内的数值，因此将其存储为未装箱的Uint8数组。因此，人们可以预期它们与强类型对应物一样有效。但是，在代码库中使用单个数组类型比使用多个数组类型更方便。

2017年，使用Buffer / Uint8Array而不是普通数组仍然有明显的性能优势吗？

Answer 1

请参阅以下用于性能测试的代码using this RunKit。它表明Buffer较慢，这与其他一些历史数据一致。

其他相关数据点：

This jsPerf
This other jsPerf

This older SO thread

//setup
//const iNumTests = 1000;
const iNumTests = 1000;
let arrResults = [];

function randomChar() {
var chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
return chars[Math.round(Math.random() * (chars.length - 1))];
}

function singleTest() {
    //buffer
    const t0 = process.hrtime();
    let buf = Buffer.from(randomChar());  //recommended to initialize with .from()
    for (var i = 1; i < iNumTests; ++i) {
        buf.write(randomChar());
    }
    var sOutput = buf.toString();
    const arrBuff = process.hrtime(t0);

    //array
    const t1 = process.hrtime();
    let chars = [];
    for (var i = 0; i < iNumTests; ++i) {
        chars.push(randomChar());
    }
    var sOutput = chars.join('');
    const arrArray = process.hrtime(t1);

    //delta
    const timeBuff = arrBuff[0] * 1e9 + arrBuff[1];
    const timeArray = arrArray[0] * 1e9 + arrArray[1];
    return (timeBuff - timeArray);
}

for (var i = 0; i < iNumTests; i++) {
    arrResults.push(singleTest());
}

var sum = arrResults.reduce(function(acc, val) {
  return acc + val;
}, 0);

console.log(sum/iNumTests);         // average difference. I got 146929.598 which means timeBuff is larger on average.

目前，使用Buffer / Uint8Array而不是普通数组有明显的性能优势吗？

1 个答案: