event.srcElement is undefined error

var cell = event.srcElement;

i t woks with IE but with FF i get event.srcElement; is undefined error

i event tried with var posx = 0;     var posy = 0;     if (!e) var e = window.event;     if (e.pageX || e.pageY)         {         posx = e.pageX;         posy = e.pageY;     }     else if (e.clientX || e.clientY)         {         posx = e.clientX + document.body.scrollLeft             + document.documentElement.scrollLeft;         posy = e.clientY + document.body.scrollTop             + document.documentElement.scrollTop;     }     var cell =e.srcElement;

but when i use the cell i get cell undefined