设立文本框只允许输入数字

function onlyNum(e){ // 只允许输入数字
		var isie = (document.all) ? true:false;
		var key;
		var ev;
		if(isie){// IE
			keyCode = window.event.keyCode;
			ev = window.event;
		}else{ // 火狐
			keyCode = e.which;
			ev = e;
		}
		if(!(keyCode==46)&&!(keyCode==8)&&!(keyCode==37)&&!(keyCode==39)&&!(keyCode==36)&&!(keyCode==35)&&!(keyCode==9)){
		// 35 36 end home 46 delete 37 39 左右 8 退格 9 Tab
			if(!((keyCode>=48&&keyCode<=57)||(keyCode>=96&&keyCode<=105))){
				if(isie){
					ev.returnValue=false;
				}else{
					ev.preventDefault();
				}
			}
		}
	}