VDragNode.onmousedown = function(e){

var ev = e || event;

var l = ev.clientX - this.offsetLeft;

document.onmousemove = function(e){

var ev = e || event;

var needX = ev.clientX - l;

var maxX = VDragNode.parentNode.offsetWidth - 2.5;

needX = needX < -2.5 ? - 2.5 : needX;

needX = needX > maxX ? maxX : needX;

//计算0 - 1

//console.log((VDragNode.offsetLeft + 2) / VDragNode.parentNode.offsetWidth);

// console.log((VDragNode.offsetLeft + 2) / VDragNode.parentNode.offsetWidth);

var lastVolume = (VDragNode.offsetLeft + 2) / VDragNode.parentNode.offsetWidth ;

VideoNode.volume = lastVolume < 0 ? 0 : lastVolume;

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

};

document.onmouseup = function(e){

document.onmousemove = document.onmouseup = null;

}

return false;

}