backbone.papertrail.js

(function (_, Backbone) {

  var PaperTrail = Backbone.PaperTrail = Backbone.Model.extend({

    store: function (options) {
      options || (options = {});

      var attrs = _.clone(this.attributes),
          same = _.isEqual(attrs, _.last(this.edits()));

      if (!same) this.edits().push(attrs);

      return this; // this is
    },

    restore: function (options) {
      options || (options = {});

      var index = options._index || 0,
          attrs = this.edits()[index];

      if (!attrs) return this;

      for (var attr in this.attributes) {
        if (!attrs[attr]) this.unset(attr);
      }

      this._edits = this.edits().slice(0, index);

      return this.set(attrs);
    },

    rollback: function (distance) {
      distance || (distance = 1);

      var index = this.edits()[0] ? (this.edits().length - distance) : 0;
      if (index < 0) index = 0;

      return this.restore({ _index: index });
    },

    wasEdited: function () {
      return !!this.edits()[0];
    },

    edits: function () {
      return this._edits || (this._edits = []);
    },

    priorAttributes: function (options) {
      options || (options = {});

      var distance = options.distance || 1,
          index = this.edits()[0] ? (this.edits().length - distance) : 0;

      return this.edits()[index];
    },

    prior: function (attr, options) {
      options || (options = {});

      var distance = options.distance || 1,
          index = this.edits()[0] ? this.edits().length - distance : 0,
          result = this.edits()[index];

      if (result) return result[attr];
    }

  });

}).call(this, _, Backbone);