Backbone.localStorage.js是将数据存储到游览器客户端本地的（当没有服务器的情况下）
地址：https://github.com/jeromegn/Backbone.localStorage
1 整个函数是一个自执行函数，简化版形式如下
(function(a,fn) {
//...
})(a,fn);
2 9-12行/**---------此处是判断上下文有没有引入AMD模块（如requirejs）-----------*/
if(typeofdefine==="function"&&define.amd) {
// AMD. Register as an anonymous module.
define(["underscore","backbone"],function(_, Backbone) {
// Use global variables if the locals are undefined.
returnfactory(_ || root._, Backbone || root.Backbone);
});
}else{
// RequireJS isn‘t being used. Assume underscore and backbone are loaded in script tags
factory(_,Backbone);
}
此种判断方法比较常见，类似的如 toastr.js种
typeofdefine===‘function‘&&define.amd?define:function(deps, factory) {
if(typeofmodule!==‘undefined‘&&module.exports) {//Node
module.exports= factory(require(‘jquery‘));
}else{
window[‘toastr‘] = factory(window[‘jQuery‘]);
}
}
/**
* Backbone localStorage Adapter
* Version 1.1.0
*
* https://github.com/jeromegn/Backbone.localStorage
*/
(function (root, factory) {
/**---------此处是判断上下文有没有引入AMD模块（如requirejs）-----------*/
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);
});
} else {
// 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.
// /**---------此处生成随机数 如 d9ab5797-9773-9bcd-27b1-9f23a3170957-----------*/
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 is deprecated, use Backbone.LocalStorage instead
/**---------定义LocalStorage函数-----------*/
Backbone.LocalStorage = window.Store = function(name) {
this.name = name;
var store = this.localStorage().getItem(this.name);
this.records = (store && store.split(",")) || [];
};
/**---------扩展LocalStorage函数 的 增删改查 等其他方法-----------*/
_.extend(Backbone.LocalStorage.prototype, {
// Save the current state of the **Store** to *localStorage*.
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();//生成唯一id
model.set(model.idAttribute, model.id);//给模型添加一条新属性id
}
this.localStorage().setItem(this.name+"-"+model.id, JSON.stringify(model));//setItem为原生localstorage的方法，此处是真正的把数据存储到客户端
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: function(model) {
return this.jsonData(this.localStorage().getItem(this.name+"-"+model.id));
},
// Return the array of all models currently in storage.
findAll: function() {
return _(this.records).chain()
.map(function(id){
return this.jsonData(this.localStorage().getItem(this.name+"-"+id));
}, this)
.compact()
.value();
},
// Delete a model from `this.data`, returning it.
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();
});
this.save();
return model;
},
localStorage: function() {
return localStorage;//返回原生的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 should be an instance of `Store`.
// window.Store.sync and Backbone.localSync is deprectated, use Backbone.LocalStorage.sync instead
Backbone.LocalStorage.sync = window.Store.sync = Backbone.localSync = function(method, model, options) {
var store = model.localStorage || model.collection.localStorage;
var resp, errorMessage, syncDfd = $.Deferred && $.Deferred(); //If $ is having Deferred - use it.//生成query的Deferred对象
//此处是一个较大的知识点，就是promise规范，和jquery的deferred 和promise 此处不展开
try {
switch (method) {
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);
if (options && options.success)
options.success(resp);
if (syncDfd)
syncDfd.resolve(resp);//回掉状态改为成功
} else {
errorMessage = errorMessage ? errorMessage
: "Record Not Found";
if (options && options.error)
options.error(errorMessage);
if (syncDfd)
syncDfd.reject(errorMessage);//回掉状态改为失败
}
// add compatibility with $.ajax
// always execute callback for success and error
if (options && options.complete) options.complete(resp);
return syncDfd && syncDfd.promise();
};
/**---------保存原来的sync-----------*/
Backbone.ajaxSync = Backbone.sync;
/**---------此处来判断返回哪个函数，用localstorage还是发送ajax-----------*/
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‘
/**---------覆盖Backbone的sync，因为原来的已经保存-----------*/
Backbone.sync = function(method, model, options) {
return Backbone.getSyncMethod(model).apply(this, [method, model, options]);
//注意：Backbone.getSyncMethod(model)返回的是一个函数，再apply(),才执行返回的这个函数
};
return Backbone.LocalStorage;
}));
时间： 2024-12-26 22:03:36