js 捕获鼠标事件

function drag(overFlow,title){

title.onmousedown = function(evt){

var doc = document;

var evt = evt || window.event;

var x = evt.offsetX?evt.offsetX:evt.layerX;

var y = evt.offsetY?evt.offsetY:evt.layerY;

if(overFlow.setCapture){

overFlow.setCapture();

}else if(window.captureEvents){

window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);

}

doc.onmousemove = function(evt){

evt = evt || window.event;

var xPosition = evt.pageX || evt.clientX;

var yPosition = evt.pageY || evt.clientY;

var newX = xPosition - x;

var newY = yPosition - y;

overFlow.style.left = newX;

overFlow.style.top = newY;

};

doc.onmouseup = function(){

if(overFlow.releaseCapture){

overFlow.releaseCapture();

}else if(window.captureEvents){

window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);

}

doc.onmousemove=null;

doc.onmouseup=null;

};

};

}