Apply CSS transformations, remembering the past history. Useful for undoable animations/transitions.

animation.js

// Undo-able CSS transformations on DOM objects
// Requires jQuery
// MIT Licensed
// Author: Aaron Zinman <aaron@azinman.com>
// Part of Defuse: http://defuse.media.mit.edu
// Tested in Safari, soon testing in: Chrome and Firefox
if (window.defuse == null) defuse = {animation:{}};

/**
 * Applies a series of CSS transformation (contained in the cssObj dictionary)
 * to the jQuery $selector. Takes a snapshot of the current CSS properties to be overriden
 * so that the previous state may be restored.
 *
 * $selector: The jQuery selector
 * cssObj: A dictionary of css values
 * disableCssTransition: If set to true, current CSS-based transitions will be temporarily turned
 *     off, to be restored to their previous value after unless a new value is in
 *     cssObj.
 */
defuse.animation.css = function($selector, cssObj, disableCssTransition) {
  // Save these settings on each element
  $selector.each(function() {
    // CSS settings for what we're about to change
    var currentSettings = {};
    var $this = $(this);
    _.each(cssObj, function(value, prop) {
      currentSettings[prop] = $this.css(prop);
    });
    // Save those settings on the DOM object
    var history = $this.data("cssHistory");
    if (history == null) {
      $this.data("cssHistory", [currentSettings]);
    } else {
      history.push(currentSettings);
      $this.data("cssHistory", history);
    }

    // Save the current transition state if necessary
    var previousTransition = $this.css("-webkit-transition");
    if (disableCssTransition) {
      $this.css({"-webkit-transition": "none",
                "-moz-transition": "none"});
    }
    // Apply changes
    $this.css(cssObj);
    // Restory previous css transition state, if it wasn't one of the things changes
    if (disableCssTransition && cssObj["-webkit-transition"] == undefined) {
      setTimeout(function() { $this.css({"-webkit-transition": previousTransition || "none",
                                         "-moz-transition": previousTransition || "none"}) }, 1);
    }
  });
};

/**
 * Undo the last group of css transformations for elements in $selector, as applied by
 * defuse.animation.css.
 *
 * $selector: jQuery selector of objects to restore
 * disableCssTransition: If set to true, current CSS-based transitions will be temporarily turned
 *     off, to be restored to their previous value after unless a new value is in
 *     cssObj.
 */
defuse.animation.undoCss = function($selector, disableCssTransition) {
  $selector.each(function() {
    $this = $(this);
    // Get history
    var history = $this.data("cssHistory");
    if (history == null || history.length == 0) return;
    var lastChanges = history.pop();
    if (history.length == 0) {
      $this.removeData("cssHistory");
    } else {
      $this.data("cssHistory", history);
    }
    // Possibly temporarily disable css transitions
    if (disableCssTransition) {
      var previousTransition = $this.css("-webkit-transition");
      $this.css({"-webkit-transition": "none",
                "-moz-transition": "none"});
    }
    // Rollback changes
    $this.css(lastChanges);
    // Restory previous css transition state, if it wasn't one of the things changes
    if (disableCssTransition && lastChanges["-webkit-transition"] == undefined) {
      setTimeout(function() { $this.css({"-webkit-transition": previousTransition || "none",
                                         "-moz-transition": previousTransition || "none"}) }, 1);
    }
  });
};