运动框架

function startMove(obj, json, fn) {
    clearInterval(obj.iTimer);
    var iCur = 0;
    var iSpeed = 0;
        
    obj.iTimer = setInterval(function() {
        
        var iBtn = true;
                    
        for ( var attr in json ) {
                            
            var iTarget = json[attr];
            
            if (attr == ‘opacity‘) {
                iCur = Math.round(css( obj, ‘opacity‘ ) * 100);
            } else {
                iCur = parseInt(css(obj, attr));
            }
            
            iSpeed = ( iTarget - iCur ) / 8;
            iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
            
            if (iCur != iTarget) {
                iBtn = false;
                if (attr == ‘opacity‘) {
                    obj.style.opacity = (iCur + iSpeed) / 100;
                    obj.style.filter = ‘alpha(opacity=‘+ (iCur + iSpeed) +‘)‘;
                } else {
                    obj.style[attr] = iCur + iSpeed + ‘px‘;
                }
            }
            
        }
        
        if (iBtn) {
            clearInterval(obj.iTimer);
            fn && fn.call(obj);
        }
        
    }, 30);
}

function css(obj, attr) {
    if (obj.currentStyle) {
        return obj.currentStyle[attr];
    } else {
        return getComputedStyle(obj, false)[attr];
    }
}