CrlNode.onmousedown = function(e){

var ev = e || event;

var l = ev.clientX - this.offsetLeft;

console.log(this.offsetLeft);

VideoNode.pause();

document.onmousemove = function(e){

var ev = e || event;

var needX = ev.clientX - l;

var maxX = LoadNode.offsetWidth - 8.5;

needX = needX < -8.5 ? -8.5 : needX;

needX = needX > maxX ? maxX : needX;

CrlNode.style.left = needX + 'px';

LineNode.style.width = (CrlNode.offsetLeft+9)/LoadNode.offsetWidth*100 + '%';

};

document.onmouseup = function(){

document.onmousemove = document.onmouseup = null;

VideoNode.currentTime = VideoNode.duration * (CrlNode.offsetLeft+9)/LoadNode.offsetWidth;

//console.log((CrlNode.offsetLeft+9)/LoadNode.offsetWidth);

//console.log()

//VideoNode.play();

//PlayBln = false;

//className = 'pauseNode';

if(PlayBln == false){

//console.log(1);

PlayNode.className = 'pauseNode';

VideoNode.play();

}

else{

//console.log(2);

PlayNode.className = 'playNode';

VideoNode.pause();

}

};

return false;

};

我console.log(this.offsetLeft); 发现结果为-9  这里的结果为什么会是-9？ 这个属性不是元素到浏览器最左边距离的属性吗？ 还有var l=event.clientX-this.offsetLeft; 这里为什么要减去这个this.offsetLeft 感觉可以直接等于event.clientX啊，求解