function proQuantity_press(evt)
    {
        evt=evt?evt:(window.event?window.event:null);
        //alert(evt);
        if ((evt.keyCode<48 || evt.keyCode>57)) 
            evt.returnValue=false;
    }调用proQuantity_press 的text是用js自动生成的:
var ec_u_quan_input = document.createElement("input");
ec_u_quan_input.type = "text";
//ec_u_quan_input.onkeydown = proQuantity_down;
//ec_u_quan_input.onkeypress = proQuantity_press;
$addHandler(ec_u_quan_input,'keydown',proQuantity_down);
$addHandler(ec_u_quan_input,'keypress',proQuantity_press);
ec_u_quan.appendChild(ec_u_quan_input);这样写的话,在IE和FF中都没有效果?请问下是什么原因?