先看以下两看计时器

setInterval

function sleep(time) { let startTime = window.performance.now(); while (window.performance.now() - startTime < time) {}}function test(){ count++; console.log(`第${count}次开始 ${getTime.now() - startTime}`); // 显示开始时间 //sleep(100); // 程序滞留500ms console.log(`第${count}次结束 ${getTime.now() - startTime}`); // 显示结束时间 count>1000 && clearInterval(t);}let count = 0;let getTime = window.performance;let startTime = getTime.now();var t = setInterval(test , 500); // 300ms间隔

最后结果：

再来看下setTimeout

function sleep(time) { let startTime = window.performance.now(); while (window.performance.now() - startTime < time) {}}function test(){ console.log(`第${count}次开始 ${getTime.now() - startTime}`); // 显示开始时间 //sleep(500); // 程序滞留500ms console.log(`第${count}次结束 ${getTime.now() - startTime}`); // 显示结束时间 count += 1; if(count<1000){setTimeout(test,500);}}var startTime0 = new Date().getTime();let count = 0;let getTime = window.performance;let startTime = getTime.now();var t;//setTimeout(test,500); // 300ms间隔setTimeout(function () { console.log(`第${count}次开始 ${getTime.now() - startTime}`); // 显示开始时间 //sleep(500); // 程序滞留500ms console.log(`第${count}次结束 ${getTime.now() - startTime}`); // 显示结束时间 count += 1; var offset = new Date().getTime() - (startTime0 + count * 500); var nextTime = 500 - offset;//console.log(nextTime); if (nextTime < 0) nextTime = 0; if(count<200){setTimeout(arguments.callee, nextTime);} }, 500)