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Immutable学习之路----告别传统拷贝

2022-06-25 04:00:00 【碰磕】

Immutable【告别传统拷贝】

immutable

首发:CSDN碰磕，学无止境
多云30°
The greatest test of courage on earth is to bear defaet without losing heart.
2022/6/24

immutable

它是一款代替传统拷贝方式的第三方库
优势:
在新对象上操作不会影响原对象的数据
性能好

安装使用

1.下载 npm i immutable
2.导入 import {Map} from 'immutable'

Map

语法:Map(对象)
赋值:set("属性名","新值")
取值:get("属性名")
toJS()转回普通对象

import React, {
     Component } from 'react';
/** * 1.下载 npm i immutable * 2.导入 import {Map} from 'immutable' */
import {
    Map} from 'immutable'

var obj={
    
    name:"碰磕",
    age:20
}
var objImmu=Map(obj);
var newobjImmu=objImmu.set("name","pengkeStudy");
// console.log(objImmu,newobjImmu)
//get('属性')获取值
console.log(objImmu.get("name"),newobjImmu.get("name"));

//toJS转回普通对象
console.log(objImmu.toJS(),newobjImmu.toJS());
/* //写法一 class Immu02 extends Component { state={ info:Map({ name:"碰磕", age:20 }) } render() { return ( <div> Immu02 <button onClick={()=>{ this.setState({ info:this.state.info.set('name',"pengkeStudy").set('age',1000) }) }}>修改它们的值</button> {this.state.info.get("name")}---- {this.state.info.get("age")} </div> ); } }*/
//写法二
class Immu02 extends Component {
    
    state={
    
        info:{
    
            name:"碰磕",
            age:20
        }
    }
    render() {
    
        return (
            <div>
                Immu02
                <button onClick={
    ()=>{
    
                    let old=Map(this.state.info)
                    let newImmu=old.set("name","pengkeStudy").set("age",10000)
                    this.setState({
    
                        info:newImmu.toJS()
                    })
                    
                }}>修改它们的值</button>
                {
    this.state.info.name}----
                {
    this.state.info.age}
            </div>
        );
    }
}

export default Immu02;

嵌套Map

Map中对象中的对象还要套上Map
可以通过map的get方法获取值向组件传值.,从而完美的解决了组件的无效刷新
shouldComponentUpdate进行判断决定是否需要刷新

import React, {
     Component } from 'react';
import {
    Map} from 'immutable'

class Immu03 extends Component {
    
    state={
    
        info:Map({
    
            name:"碰磕",
            age:20,
            hobbit:Map({
    
                likeone:"运动",
                liketwo:"学习"
            })
        })
    }
    render() {
    
        return (
            <div>
                Immu03
                <button onClick={
    ()=>{
    this.setState({
    
                    info:this.state.info.set("name","学习啊啊啊")
                })}}>修改</button>
                {
    this.state.info.get("name")}
                <Child hobbit={
    this.state.info.get("hobbit")} ></Child> 
            </div>
        );
    }
}
class Child extends Component{
    
    shouldComponentUpdate(nextProps,nextState){
    
        //判断hobbit的值是否更新
        if(this.props.hobbit===nextProps.hobbit){
    
            return false;
        }
        return true;
    }
    render(){
    
        return(
            <div>Child</div>
        );
    }
    componentDidUpdate(){
    
        console.log("子组件更新了");
    }
}
export default Immu03;

List

可以使用数组的属性方法

import React, {
     Component } from 'react';
import {
    List} from 'immutable'
var arr=List([1,231,1])
let arr2=arr.push(4)//不会影响原对象结构
let arr3=arr2.concat([12,323,123])
console.log(arr,arr2,arr3);
class Immu04 extends Component {
    
    state={
    
        favor:List(['吃饭','睡觉','学习','运动'])
    }
    render() {
    
        return (
            <div>
                Immu04
                {
    
                    this.state.favor.map(item=>{
    
                        return <li key={
    item}>{
    item}</li>
                    })
                }
            </div>
        );
    }
}
export default Immu04;

实现个人修改案例

import {
     List,Map } from 'immutable';
import React, {
     Component } from 'react';
class Immu05 extends Component {
    
    state={
    
        info:Map({
    
            name:"碰磕",
            location:Map({
    
                province:"江西",
                city:"吉安"
            }),
            hobbit:List(['睡觉','学习','敲键盘'])
        })
    }
    render() {
    
        return (
            <div>
                <h1>编辑个人信息</h1>
                <div>
                    <button onClick={
    ()=>{
    
                        this.setState({
    
                            info:this.state.info.set("name","爱学习").set("location",this.state.info.get("location").set("city","南昌"))
                        })
                    }}>修改</button>
                    {
    this.state.info.get("name")}
                    <br />
                    {
    this.state.info.get("location").get("province")}-
                    {
    this.state.info.get("location").get("city")}
                    {
    
                        this.state.info.get("hobbit").map((item,index)=><li key={
    item}>{
    item}<button onClick={
    ()=>{
    
                            // console.log(index);
                            this.setState({
    
                                info:this.state.info.set("hobbit",this.state.info.get("hobbit").splice(index,1))
                            })
                        }}>删除</button></li>)
                    }
                </div>
            </div>
        );
    }
}

export default Immu05;

通过fromJS、setIn、updateIn进行改进

fromJS将普通对象转换为Immutable
setIn()深度赋值,参数一为数组形式填写需要修改的，参数二为修改后的值
updateIn()深度修改，参数一为数组形式填写需要修改的，参数二为回调函数(参数为原对象)

import {
     fromJS } from 'immutable';
import React, {
     Component } from 'react';
class Immu06 extends Component {
    
    state={
    
        info:fromJS({
    
            name:"碰磕",
            location:{
    
                province:"江西",
                city:"吉安"
            },
            hobbit:['睡觉','学习','敲键盘']
        })
    }

    render() {
    
        return (
            <div>
                <h1>编辑个人信息</h1>
                <div>
                    <button onClick={
    ()=>{
    
                        this.setState({
    
                            info:this.state.info.setIn(["name"],"爱学习").setIn(["location","city"],"南昌")//setIn("参数一为数组","修改后的值")
                        })
                    }}>修改</button>
                    {
    this.state.info.get("name")}
                    <br />
                    {
    this.state.info.get("location").get("province")}-
                    {
    this.state.info.get("location").get("city")}
                    {
    
                        this.state.info.get("hobbit").map((item,index)=><li key={
    item}>{
    item}<button onClick={
    ()=>{
    
                            // console.log(index);
                            // this.setState({
    
                            // info:this.state.info.setIn(["hobbit",index],"")
                            // })
                            //updateIn(需要修改的对象,回调函数(参数为原对象))
                            this.setState({
    
                                info:this.state.info.updateIn(["hobbit"],(list)=>list.splice(index,1))
                            })
                        }}>删除</button></li>)
                    }
                </div>
            </div>
        );
    }
}

export default Immu06;