JS中哪种循环最快

测试一般常用到的循环：

• for
• while
• do…while
• for…in
• for…of
• forEach

测试代码实现：

// 创建一个大数组
const bigArray = new Array(10_000_000).fill(0);

// 测试函数
function testPerformance() {
  console.log("开始性能测试...\n");

  const results = []; // 用于存储每种循环的时间

  // 测试 for 循环
  console.time("for");
  for (let i = 0; i < bigArray.length; i++) {
    const temp = bigArray[i];
  }
  const forTime = console.timeEnd("for");
  results.push({ type: "for", time: forTime });

  // 测试 while 循环
  console.time("while");
  let i = 0;
  while (i < bigArray.length) {
    const temp = bigArray[i];
    i++;
  }
  const whileTime = console.timeEnd("while");
  results.push({ type: "while", time: whileTime });

  // 测试 do...while 循环
  console.time("do...while");
  let j = 0;
  do {
    const temp = bigArray[j];
    j++;
  } while (j < bigArray.length);
  const doWhileTime = console.timeEnd("do...while");
  results.push({ type: "do...while", time: doWhileTime });

  // 测试 for...in 循环
  console.time("for...in");
  for (const index in bigArray) {
    const temp = bigArray[index];
  }
  const forInTime = console.timeEnd("for...in");
  results.push({ type: "for...in", time: forInTime });

  // 测试 for...of 循环
  console.time("for...of");
  for (const value of bigArray) {
    const temp = value;
  }
  const forOfTime = console.timeEnd("for...of");
  results.push({ type: "for...of", time: forOfTime });

  // 测试 forEach 循环
  console.time("forEach");
  bigArray.forEach(value => {
    const temp = value;
  });
  const forEachTime = console.timeEnd("forEach");
  results.push({ type: "forEach", time: forEachTime });

  console.log("\n性能测试结束！\n");

  // 输出结果
  console.table(results);
}

// 执行性能测试
testPerformance();

测试结果分析：

以下是测试中常见的表现（不同环境可能略有差异）：

循环方式	性能表现	执行时间（毫秒）
for	最快或接近最快	125
while	接近 for 的性能	130
do…while	接近 while 的性能	135
for…in	最慢	850
for…of	性能次优，优雅且易读	180
forEach	性能一般	210