Timelapse CSS

//  Timelapse CSS functions by Karl von Randow, May 2008

var timelapseCss = function() {
	var interval = 100;

	function removeARule(attributes, state) {
		if (state.k < attributes.length) {
			var attribute = attributes[attributes.length - 1 - state.k];
			var r = attributes.removeProperty(attribute);
			if (!r) {
				state.k++;
			}
			return true;
		} else {
			return false;
		}
	}

	function disableARule(attributes, state) {
		if (attributes == null) return false;
		//state.i+=10;
		if (state.k < attributes.length) {
			var attribute = attributes[attributes.length - 1 - state.k];
			var value = attributes.getPropertyValue(attribute);
			var key = "i" + state.ipos + "j" + state.jpos;
			if (state.disabled[key] == null) {
				state.disabled[key] = [];
			}
			state.disabled[key].push({attribute:attribute, value:value});
			return removeARule(attributes, state);
		} else {
			return false;
		}
	}

	function enableARule(attributes, state) {
		var key = "i" + state.ipos + "j" + state.jpos;
		var d = state.disabled[key];
		if (d != null && state.k < d.length) {
			attributes.setProperty(d[d.length - 1 - state.k].attribute, d[d.length - 1 - state.k].value);
			state.k++;
			return true;
		} else {
			return false;
		}
	}

	function iterateRules(action, state, async) {
		while (true) {
			if (state.i < document.styleSheets.length) {
				state.ipos = state.forwards ? state.i : document.styleSheets.length - 1 - state.i;
				var rules = document.styleSheets[state.ipos].cssRules;
				if (state.j < rules.length) {
					state.jpos = state.forwards ? state.j : rules.length - 1 - state.j;
					var attributes = rules[state.jpos].style;
					var cont = action(attributes, state);
					if (cont) {
						if (async)
							setTimeout(function() {
								iterateRules(action, state, async);
							}, interval);
						return true;
					} else {
						state.k = 0;
						state.j++;
					}
				} else {
					state.j = 0;
					state.i++;
				}
			} else {
				return false;
			}
		}
	}

	return {
		timelapseRemoveCss: function() {
			var state = {i:0, j:0, k:0, forwards:false};
			iterateRules(removeARule, state, true);
		},

		removeCss: function() {
			var state = {i:0, j:0, k:0, forwards:false};
			while (iterateRules(removeARule, state, false));
		},

		timelapseApplyCss: function() {
			var state = {i:0, j:0, k:0, forwards:false, disabled:[]};
			while (iterateRules(disableARule, state, false));
			state = {i:0, j:0, k:0, forwards:true, disabled:state.disabled};
			iterateRules(enableARule, state, true);
		}
	};
}();

timelapseCss.timelapseApplyCss();