アニメーションするやつ

animate

function animate(elem, styles, duration, easing) {
	var dfd = new Deferred(),
		fps = undefined,
		current_time = 0,
		style_key = undefined,
		start_value = undefined,
		end_value = undefined,
		pt = '',
		rev = false,
		diff_start = 0,
		diff = undefined,
		current_style = getComputedStyle(elem),
		easing_func = {
			swing: function (t, b, c, d) {
				return -c * (t /= d) * (t - 2) + b;
			}
		};

	_.each(styles, function(val, key) {
		style_key = key;
		start_value = current_style[key];
	});

	duration = duration * 1000;
	fps = duration / 30;
	easing = easing ? easing : 'swing';
	end_value = styles[style_key];

	if ( /top|margin|left/.test(style_key) ) {
		if ( start_value === 'auto' ) start_value = 0;
		start_value = parseFloat(start_value, 10);
		end_value = parseFloat(start_value) + end_value;
		pt = 'px';
	} else {
		start_value = parseFloat(start_value, 10);
	}

	if ( start_value > end_value ) {
		rev = true;
		diff = start_value - end_value;
	} else {
		diff = end_value - start_value;
	}

	(function() {
		var res = easing_func[easing](current_time, diff_start, diff, fps),
			value = (rev ? start_value - res : res);

		elem.style[style_key] = value + pt;
		current_time = current_time + 1;
		if ( current_time > fps ) return;

		setTimeout(arguments.callee, duration / fps);
	}());
}