improve backbone localstorage by wrapping it in in an IIFE and creati…

…ng a Backbone.Store constructor, as well as allowing for storage in SessionStorage in addition to LocalStorage.

sorry for the non-atomic commit

backbone.localStorage.js

@@ -1,94 +1,114 @@
-// A simple module to replace `Backbone.sync` with *localStorage*-based
-// persistence. Models are given GUIDS, and saved into a JSON object. Simple
-// as that.
-
-// Generate four random hex digits.
-function S4() {
-   return (((1+Math.random())*0x10000)|0).toString(16).substring(1);
-};
-
-// Generate a pseudo-GUID by concatenating random hexadecimal.
-function guid() {
-   return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());
-};
-
-// Our Store is represented by a single JS object in *localStorage*. Create it
-// with a meaningful name, like the name you'd give a table.
-window.Store = function(name) {
-  this.name = name;
-  var store = localStorage.getItem(this.name);
-  this.records = (store && store.split(",")) || [];
-};
-
-_.extend(Store.prototype, {
-
-  // Save the current state of the **Store** to *localStorage*.
-  save: function() {
-    localStorage.setItem(this.name, this.records.join(","));
-  },
-
-  // Add a model, giving it a (hopefully)-unique GUID, if it doesn't already
-  // have an id of it's own.
-  create: function(model) {
-    if (!model.id) model.id = model.attributes.id = guid();
-    localStorage.setItem(this.name+"-"+model.id, JSON.stringify(model));
-    this.records.push(model.id.toString());
-    this.save();
-    return model;
-  },
-
-  // Update a model by replacing its copy in `this.data`.
-  update: function(model) {
-    localStorage.setItem(this.name+"-"+model.id, JSON.stringify(model));
-    if (!_.include(this.records, model.id.toString())) this.records.push(model.id.toString()); this.save();
-    return model;
-  },
-
-  // Retrieve a model from `this.data` by id.
-  find: function(model) {
-    return JSON.parse(localStorage.getItem(this.name+"-"+model.id));
-  },
-
-  // Return the array of all models currently in storage.
-  findAll: function() {
-    return _.map(this.records, function(id){return JSON.parse(localStorage.getItem(this.name+"-"+id));}, this);
-  },
-
-  // Delete a model from `this.data`, returning it.
-  destroy: function(model) {
-    localStorage.removeItem(this.name+"-"+model.id);
-    this.records = _.reject(this.records, function(record_id){return record_id == model.id.toString();});
-    this.save();
-    return model;
-  }
+(function(_, Backbone) {
+  // A simple module to replace `Backbone.sync` with *localStorage*-based
+  // persistence. Models are given GUIDS, and saved into a JSON object. Simple
+  // as that.
+  // Generate four random hex digits.
 
-});
 
-// Override `Backbone.sync` to use delegate to the model or collection's
-// *localStorage* property, which should be an instance of `Store`.
-Backbone.sync = function(method, model, options, error) {
+  function S4() {
+      return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
+  };
 
-  // Backwards compatibility with Backbone <= 0.3.3
-  if (typeof options == 'function') {
-    options = {
-      success: options,
-      error: error
-    };
-  }
+  // Generate a pseudo-GUID by concatenating random hexadecimal.
 
-  var resp;
-  var store = model.localStorage || model.collection.localStorage;
 
-  switch (method) {
-    case "read":    resp = model.id ? store.find(model) : store.findAll(); break;
-    case "create":  resp = store.create(model);                            break;
-    case "update":  resp = store.update(model);                            break;
-    case "delete":  resp = store.destroy(model);                           break;
-  }
+  function guid() {
+      return (S4() + S4() + "-" + S4() + "-" + S4() + "-" + S4() + "-" + S4() + S4() + S4());
+  };
 
-  if (resp) {
-    options.success(resp);
-  } else {
-    options.error("Record not found");
+  Backbone.Store = function (name,type) {
+      type = type || "local";
+      this.name = name;
+      this.type = type + "Storage";
+      var store = window[this.type].getItem(this.name);
+      this.records = (store && store.split(",")) || [];
   }
-};
+
+  _.extend(Backbone.Store.prototype, {
+
+      // Save the current state of the **Store** to *localStorage*.
+      save: function() {
+          window[this.type].setItem(this.name, this.records.join(","));
+      },
+
+      // Add a model, giving it a (hopefully)-unique GUID, if it doesn't already
+      // have an id of it's own.
+      create: function(model) {
+          if (!model.id) model.id = model.attributes.id = guid();
+          window[this.type].setItem(this.name + "-" + model.id, JSON.stringify(model));
+          this.records.push(model.id.toString());
+          this.save();
+          return model;
+      },
+
+      // Update a model by replacing its copy in `this.data`.
+      update: function(model) {
+          window[this.type].setItem(this.name + "-" + model.id, JSON.stringify(model));
+          if (!_.include(this.records, model.id.toString())) this.records.push(model.id.toString());
+          this.save();
+          return model;
+      },
+
+      // Retrieve a model from `this.data` by id.
+      find: function(model) {
+          return JSON.parse(window[this.type].getItem(this.name + "-" + model.id));
+      },
+
+      // Return the array of all models currently in storage.
+      findAll: function() {
+          return _.map(this.records, function(id) {
+              return JSON.parse(window[this.type].getItem(this.name + "-" + id))
+          }, this);
+      },
+
+      // Delete a model from `this.data`, returning it.
+      destroy: function(model) {
+          window[this.type].removeItem(this.name + "-" + model.id);
+          this.records = _.reject(this.records, function(record_id) {
+              return record_id == model.id.toString();
+          });
+          this.save();
+          return model;
+      }
+
+
+  });
+
+
+  // Override `Backbone.sync` to use delegate to the model or collection's
+  // *localStorage* property, which should be an instance of `Store`.
+  Backbone.sync = function(method, model, options, error) {
+
+    // Backwards compatibility with Backbone <= 0.3.3
+    if (typeof options == 'function') {
+      options = {
+        success: options,
+        error: error
+      };
+    }
+
+    var resp,
+        store =  model.localStorage || model.sessionStorage;
+
+      if (!store && model.collection) {
+        store = model.collection.localStorage || model.collection.sessionStorage;
+      }
+      if (!store) {
+        return error("No storage found");
+      }
+
+      switch (method) {
+      case "read":    resp = model.id ? store.find(model) : store.findAll(); break;
+      case "create":  resp = store.create(model);                            break;
+      case "update":  resp = store.update(model);                            break;
+      case "delete":  resp = store.destroy(model);                           break;
+      }
+
+      if (resp) {
+        options.success(resp);
+      } else {
+        options.error("Record not found");
+      }
+  };
+
+})(_, Backbone);