JS onkeydown绑定的函数怎么返回值

[yredred]

document.onkeydown=move;
function move() {
        var code = event.keyCode;
        var direction;
        if(code == 37){
            direction = 3;
        }
        else if (code ==38){
            direction = 4;
        }
        else if (code ==39){
            direction = 1;
        }
        else if (code == 40){
            direction = 2;
        }

        console.log(direction);
        return direction;         //怎么实现函数外部得到direction值
    }

[___紫菜]

document.onkeydown=function () { var sd =move(); console.log(sd); };

[囧]

用全局变量或者回调函数