let video1 = document.getElementById("video1"); let video2 = document.getElementById("video2"); video1.play(); window.onscroll = function () { var t = document.documentElement.scrollTop || document.body.scrollTop; //变量t就是滚动条滚动时,到顶部的距离 console.log(video2.pause); // video2.pause() if (t < 700) { video2.pause(); video1.play(); } else if (t >= 700) { video1.pause(); video2.play(); } }