event.clientX的问题

Question

function cnvs_getCoordinates(e){x=e.clientX;y=e.clientY;document.getElementById("xycoordinates").innerHTML="Coordinates: (" + x + "," + y + ")";}为什么非要传个参数,有什么好处,下面这么些有什么不同?function cnvs_getCoordinates(){x=event.clientX;y=event.clientY;document.getElementById("xycoordinates").innerHTML="Coordinates: (" + x + "," + y + ")";}

Answer 1

传参是为了兼容,因为有的浏览器不兼容 event 属性

这是就会在函数的内部开头增加一行代码 var ev = e || window.event;