任意值的运动框架

function getStyle(obj, name) {//获取样式
    if (obj.currentStyle) {
        return obj.currentStyle[name];
    }
    else {
        return getComputedStyle(obj, false)[name];
    }
}

function startMove(obj, attr, iTarget) {//设置样式
    clearInterval(obj.timer);
    obj.timer = setInterval(function () {
        var cur = 0;

        if (attr == 'opacity') {//透明度特殊情况
            cur = Math.round(parseFloat(getStyle(obj, attr)) * 100);
        }
        else {
            cur = parseInt(getStyle(obj, attr));
        }

        var speed = (iTarget - cur) / 6;
        speed = speed > 0 ? Math.ceil(speed) : Math.floor(speed);

        if (cur == iTarget) {
            clearInterval(obj.timer);
        }
        else {
            if (attr == 'opacity') {
                obj.style.filter = 'alpha(opacity:' + (cur + speed) + ')';
                obj.style.opacity = (cur + speed) / 100;

                document.getElementById('txt1').value = obj.style.opacity;
            }
            else {
                obj.style[attr] = cur + speed + 'px';
            }
        }
    }, 30);
}