Backbone learning: backbone. localStorage. js

In the previous article, we used this file. Now let's simply analyze its mechanism. Let's just look at the comment and then OK:

/*** Backbone localStorage Adapter * Version 1.1.0 ** https://github.com/jeromegn/Backbone.localStorage */(function (root, factory) {if (typeof define = "function" & define. amd) {// AMD. register as an anonymous module. define (["underscore", "backbone"], function (_, Backbone) {// Use global variables if the locals are undefined. return factory (_ | root. _, Backbone | root. backbone) ;}) ;}e Lse {// RequireJS isn' t being used. assume underscore and backbone are loaded in <script> tags factory (_, Backbone) ;}( this, 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. // Hold reference to Underscore. js and Backbone. js in the closure in order // to make things Work even if they are removed from the global namespace // 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. // generate guidfunction guid () {return (S4 () + S4 () + "-" + S4 () + "-" + S4 () + "-" + S4 () + "-" + S4 () + S4 () + S4 ());}; // Our Store is represented by a single JS object in * localStorage *. cr Eate it // with a meaningful name, like the name you 'd give a table. // window. store is deprectated, use Backbone. localStorage insteadBackbone. localStorage = window. store = function (name) {this. name = name; // the key value is stored in the key var store = this in localStorage. localStorage (). getItem (this. name); // obtain the data stored in localStorage. records = (store & store. split (",") | []; // All records are separated by commas };_. extend (Backbone. loca LStorage. prototype, {// Save the current state of the ** Store ** to * localStorage *. // (re) save all records save: function () {this. 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 = guid (); model. set (model. idAttribute, model. id);} this. localStorage (). setItem (this. name + "-" + model. id, JSON. stringify (model); this. records. push (model. id. toString (); this. save (); return this. find (model) ;}, // Update a model by replacing its copy in 'this. data '. // update: function (model) {this. 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 this. find (model) ;}, // Retrieve a model from 'this. data 'by id. // find data find: function (model) {return this based on the model id. jsonData (this. localStorage (). getItem (this. name + "-" + model. id) ;}, // Return the array of all models currently in storage. // obtain all data findAll: function () {return _ (this. recor Ds ). chain (). map (function (id) {return this. jsonData (this. localStorage (). getItem (this. name + "-" + id) ;}, this ). compact (). value () ;}, // Delete a model from 'this. data', returning it. // delete a data record. destroy: function (model) {if (model. isNew () return false this. localStorage (). removeItem (this. name + "-" + model. id); this. records = _. reject (this. records, function (id) {return id = model. id. toString () ;}); t His. save (); return model;}, localStorage: function () {return localStorage;}, // fix for "illegal access" error on Android when JSON. parse is passed null jsonData: function (data) {return data & JSON. parse (data) ;}}); // localSync delegate to the model or collection's // * localStorage * property, which shocould be an instance of 'store '. // window. store. sync and Backbone. localSync is deprectated, us E Backbone. localStorage. sync instead // encapsulate the local analog interface Backbone. localStorage. sync = window. store. sync = Backbone. localSync = function (method, model, options) {// The localStorage parameter in the model or the localStorage parameter in the collection. // It is a Store instantiated object var store = model. localStorage | model. collection. localStorage; var resp, errorMessage, syncDfd = $. deferred & $. deferred (); // If $ is having Deferred-use it. try {switch (Method) {// process different request methods: read (GET) create (POST) update (PUT) delete (DELETE) case "read": resp = model. id! = Undefined? 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;} catch (error) {if (error. code = DOMException. QUOTA_EXCEEDED_ERR & window. localStorage. length = 0) errorMessage = "Private browsing is unsupported"; else errorMessage = error. message;} if (resp ){ Model. trigger ("sync", model, resp, options); // execute the callback if (options & options. success) options. success (resp); if (syncDfd) syncDfd. resolve (resp);} else {errorMessage = errorMessage? ErrorMessage: "Record Not Found"; if (options & options. error) options. error (errorMessage); if (syncDfd) syncDfd. reject (errorMessage);} // add compatibility with $. ajax // always execute callback for success and error if (options & options. complete) options. complete (resp); return syncDfd & syncDfd. promise () ;}; Backbone. ajaxSync = Backbone. sync; Backbone. getSyncMethod = function (model) {if (model. localStorage | (model. collection & model. collection. localStorage) {return Backbone. localSync;} return Backbone. ajaxSync;}; // Override 'backbone. sync 'to default to localSync, // the original' Backbone. sync 'is still available in' Backbone. ajaxSync '// rewrite the Backbone sync function, so that the default request of the program can be forwarded to the Store to process the Backbone. sync = function (method, model, options) {return Backbone. getSyncMethod (model ). apply (this, [method, model, options]) ;}; return Backbone. localStorage ;}));

Welcome to the guidance and suggestions.