How to use localstorage and sessionstorage in Vue-JS Tutorial-php.cn

This time I will bring you how to use localstorage and sessionstorage in Vue. What are the precautions for using localstorage and sessionstorage in Vue. The following is a practical case. Get up and take a look.

1. Several problems exposed during the use of the project

Everyone directly uses localstorage['aaa']='This is an example string' and these native syntax implementations. This coupling is too high. If one day we need to change the implementation method, or adjust the storage size If you do some control, there will be a lot of code that needs to be modified

If the project is very large, the key names given by everyone will inevitably be repeated, and this will also cause global pollution

Because the use of localstorage is not standardized, it results in waste and insufficient storage space

2. Solution

Encapsulate the usage of storage and handle it uniformly

Standardize the naming rules for storage key values
Standardize the usage specifications of storage

2.1. Encapsulate a unified method

Encapsulating into methods can reduce coupling, facilitate switching of implementation methods, and control the storage size

Changing the implementation can be achieved by configuring different parameters

Edit the project structure as shown

Code implementation

/*
 * storage.js
 */
/*
 * @Author: 石国庆
 * @Desc: 本地数据存储方法封装
 * @Date: 2017.11.14
 * @Ref:
 *  https://github.com/WQTeam/web-storage-cache
 *  https://developer.mozilla.org/en-US/docs/Web/API/Storage/LocalStorage
 * @Explain:为了不new对象，只能多写几遍
 * @Example:
 *
 * 1、LocalStorage的使用
 * import storage from '@/utils/storage.js'
 * storage.setItem('shiguoqing0',[1,2,3,4,5,6])
 * storage.setItem('shiguoqing1',{userId:'dfdf',token:11232323})
 * storage.setItem('shiguoqing2','dfdfdf')
 * console.log(storage.getItem('shiguoqing0'))
 * console.log(storage.getItem('shiguoqing1'))
 * console.log(storage.getItem('shiguoqing2'))
 * storage.removeItem('shiguoqing2')
 *
 *
 * 2、SessionStorage的使用
 * storage.setItem('shiguoqing0',[1,2,3,4,5,6],{type:'session'})
 *
 * */
// TODO:其他方法的实现
// TODO:超时时间的设置
/*
 * 方法实现
 * */
import local from './storage/localstorage.js'
import session from './storage/session.js'
import cookies from './storage/cookies.js'
import json from './storage/json.js'
/*
* 函数体
* */
let storage= {
 config:{
  type:'local',// local,session,cookies,json
  expires:new Date().getTime() + 100 * 24 * 60 * 60 * 1000
 },
 getStorage(options){
  let config={}
  if(options){
   config=Object.assign({},this.config,options)
  }else{
   config=this.config
  }
  return this.createStorage(config.type)
 },
 createStorage(name){
  switch(name){
   case 'local':return local;break
   case 'session':return session;break
   case 'cookies':return cookies;break
   case 'json':return json;break
  }
 },
 getItem(key,options){
  let store=this.getStorage(options)
  return store.getItem(key)
 },
 setItem(key, value,options){
  let store=this.getStorage(options)
  store.setItem(key,value)
 },
 removeItem(key,options){
  let store=this.getStorage(options)
  store.removeItem(key)
 },
 getAll(){},
 clear(options){
  let store=this.getStorage(options)
  store.clear()
 },
 key(n){},
 lenght(){},
 has(key){},
 forEach(cb){},
 deleteAllExpires(){},
 // 获取最大存储空间：只有LocalStorage和SessionStorage可以使用这个方法
 getMaxSpace(options){
  let store=this.getStorage(options)
  store.getMaxSpace()
 },
 // 获取使用了的空间：只有LocalStorage和SessionStorage可以使用这个方法
 getUsedSpace(options){
  let store=this.getStorage(options)
  store.getUsedSpace()
 }
}
export default storage
// https://segmentfault.com/a/1190000002458488
// 5、遍历localStorage存储的key
//  .length 数据总量，例：localStorage.length
//  .key(index) 获取key，例：var key=localStorage.key(index);
// 备注：localStorage存数的数据是不能跨浏览器共用的，一个浏览器只能读取各自浏览器的数据,储存空间5M。
// 超时设置
// function(st, key, value, expires) {
//  if (st == 'l') {
//   st = window.localStorage;
//   expires = expires || 60;
//  } else {
//   st = window.sessionStorage;
//   expires = expires || 5;
//  }
//  if (typeof value != 'undefined') {
//   try {
//    return st.setItem(key, JSON.stringify({
//     data: value,
//     expires: new Date().getTime() + expires * 1000 * 60
//    }));
//   } catch (e) {}
//  } else {
//   var result = JSON.parse(st.getItem(key) || '{}');
//   if (result && new Date().getTime() < result.expires) {
//    return result.data;
//   } else {
//    st.removeItem(key);
//    return null;
//   }
//  }
// }

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/*
 * localstorage.js
 * localstorage的实现
 */
// 这个有点奇怪,文件名称叫local.js不能按照js文件解析
export default {
 getItem(key){
  let item = localStorage.getItem(key)
  // 这点要判断是字符串还是对象
  let result = /^[{\[].*[}\]]$/g.test(item)
  if (result) {
   return JSON.parse(item)
  } else {
   return item
  }
 },
 setItem(key, value){
  // 这点要判断是字符串还是对象
  if (typeof value == "string") {
   localStorage.setItem(key, value)
  } else {
   let item = JSON.stringify(value)
   localStorage.setItem(key, item)
  }
 },
 removeItem(key){
  localStorage.removeItem(key)
 },
 getAll(){},
 clear(){
  localStorage.clear()
 },
 key(n){},
 forEach(cb){},
 has(key){},
 deleteAllExpires(){},
 // 获取localstorage最大存储容量
 getMaxSpace(){
  if (!window.localStorage) {
   console.log('当前浏览器不支持localStorage!')
  }
  var test = '0123456789'
  var add = function (num) {
   num += num
   if (num.length == 10240) {
    test = num
    return
   }
   add(num)
  }
  add(test)
  var sum = test
  var show = setInterval(function () {
   sum += test
   try {
    window.localStorage.removeItem('test')
    window.localStorage.setItem('test', sum)
    console.log(sum.length / 1024 + 'KB')
   } catch (e) {
    console.log(sum.length / 1024 + 'KB超出最大限制')
    clearInterval(show)
   }
  }, 0.1)
 },
 // 获取使用了的localstorage的空间
 getUsedSpace(){
  if (!window.localStorage) {
   console.log('浏览器不支持localStorage')
  }
  var size = 0
  for (item in window.localStorage) {
   if (window.localStorage.hasOwnProperty(item)) {
    size += window.localStorage.getItem(item).length
   }
  }
  console.log('当前localStorage使用容量为' + (size / 1024).toFixed(2) + 'KB')
 }
}

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/*
 * session.js
 * sessionstorage的实现
 */
export default {
 getItem(key){
  let item = sessionStorage.getItem(key)
  // 这点要判断是字符串还是对象
  let result = /^[{\[].*[}\]]$/g.test(item)
  if (result) {
   return JSON.parse(item)
  } else {
   return item
  }
 },
 setItem(key, value){
  // 这点要判断是字符串还是对象
  if (typeof value == "string") {
   sessionStorage.setItem(key, value)
  } else {
   let item = JSON.stringify(value)
   sessionStorage.setItem(key, item)
  }
 },
 removeItem(key){
  sessionStorage.removeItem(key)
 },
 getAll(){},
 clear(){
  sessionStorage.clear()
 },
 key(n){},
 forEach(cb){},
 has(key){},
 deleteAllExpires(){},
 // 获取localstorage最大存储容量
 getMaxSpace(){
  if (!window.sessionStorage) {
   console.log('当前浏览器不支持sessionStorage!')
  }
  var test = '0123456789'
  var add = function (num) {
   num += num
   if (num.length == 10240) {
    test = num
    return
   }
   add(num)
  }
  add(test)
  var sum = test
  var show = setInterval(function () {
   sum += test
   try {
    window.sessionStorage.removeItem('test')
    window.sessionStorage.setItem('test', sum)
    console.log(sum.length / 1024 + 'KB')
   } catch (e) {
    console.log(sum.length / 1024 + 'KB超出最大限制')
    clearInterval(show)
   }
  }, 0.1)
 },
 // 获取使用了的localstorage的空间
 getUsedSpace(){
  if (!window.sessionStorage) {
   console.log('浏览器不支持sessionStorage')
  }
  var size = 0
  for (item in window.sessionStorage) {
   if (window.sessionStorage.hasOwnProperty(item)) {
    size += window.sessionStorage.getItem(item).length
   }
  }
  console.log('当前sessionStorage使用容量为' + (size / 1024).toFixed(2) + 'KB')
 }
}

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/*
 * cookies.js
 * cooikes的实现，这辈子估计没有时间实现了
 */
export default {
 getItem(key){},
 setItem(key, value){},
 removeItem(key){},
 getAll(){},
 clear(){},
 key(n){},
 forEach(cb){},
 has(key){},
 deleteAllExpires(){}
}

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/*
 * json.js
 * json的实现，这辈子估计也没有时间实现了
 */
export default {
 getItem(key){},
 setItem(key, value){},
 removeItem(key){},
 getAll(){},
 clear(){},
 key(n){},
 forEach(cb){},
 has(key){},
 deleteAllExpires(){}
}

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2.2. Standardize the use of namespace

In order to prevent key value pollution, we can use the namespace reasonably

We can define a namespace, but we cannot store a lot of data in the same object, so the amount of subsequent operations will be too large

For example, the global one is under global

For example, add the system affix

to each functional system The namespace specification of a system should be designed in advance, otherwise many people will not follow the rules when it is actually developed

Things used globally should be reflected in the README.md document

Example

* localStorage['SGQ.global.userAuthor']：登录的用户信息都在这里,菜单,组织，集团
* localStorage['SGQ.global.systemName']：登录的系统名称
* localStorage['SGQ.vuex.state']:vuex中的state的存储地址，这里面有所有的的东西
* localStorage['SGQ.wms.warehouse']:wms需要的仓库信息
+ localStorage['SGQ.wms.warehouse'].permissionId
+ localStorage['SGQ.wms.warehouse'].dataResource
* localStorage['SGQ.tms.org']:tms需要的网点的信息
+ localStorage['SGQ.tms.org'].permissionId
+ localStorage['SGQ.tms.org'].orgName

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2.3. Storage usage specifications

2.3.1. Cause of the problem

This problem arises because we need to log in with permissions, and then when logging in, it keeps reporting that there is insufficient storage space. After checking the reason, we found that the backend returned all the thousands of super-managed data, so that there was not enough space. , and later modified the data content returned by the backend interface to solve this problem.

But what did this incident bring us to think about?

The storage capacity of localstorage and sessionstorage is basically 5M in different browsers

The storage of localstorage and sessionstorage follows the domain name

The localstorage storage under boss.hivescm.com is 5M

The localstorage storage under b2b.hivescm.com is also 5M

Even if the problem is solved this time, we should make a plan to make full use of the total 10M space of localstorage and sessionstorage under one domain name

2.3.2. storage usage plan

Things used globally, things shared, and things permanently stored are stored in localstorage

Remember to clear things that do not need permanent storage after use

If the amount of data is too large, do not store it locally and obtain it dynamically

You can use Indexeddb with larger storage capacity, but there are compatibility issues

You can set a word limit on the things to be stored in storage in the implementation plan

Make full and reasonable use of the H5 features of sessionstorage and localstorage

For example: list data stored in vuex will also be stored in localstorage

For example: some data for form verification uses sessionstorage

3. Others

3.1. Extension

This can be deduced to the processing of events. Useless events should be cleaned up in time when exiting the vue component

For example: this.bus.$on('aa') should use this.bus.$off('aa') to unload the event

3.2. 字符长短获取

var len = 0
for (var i = 0; i < val.length; i++) {
 if (val[i].match(/[^\x00-\xff]/ig) != null) //全角
  len += 2 //如果是全角，占用两个字节 如果mysql中某字段是text, 如果设置编码为utf-8,那么一个中文是占3个字节, gbk是两个字节
 else
  len += 1 //半角占用一个字节
}
return len

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