伸缩放大的js

window.onload = function() {
        var div1 = document.getElementById('div1');
        div1.onmouseover = function(){
             startMove(this,400);
        }
        div1.onmouseout = function(){
             startMove(this,200);
        }

function startMove(obj, iTarget) {
            clearInterval(obj.timer);
            obj.timer = setInterval(
                function() {
                    var speed = (iTarget-obj.offsetHeight)/3;
                    obj.style.height = obj.offsetHeight + speed + 'px';
                    obj.style.width = obj.offsetWidth + speed + 'px';                
                }, 30)
        };
    }