Immutable學習之路----告別傳統拷貝

首發:CSDN碰磕，學無止境

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多雲30°

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The greatest test of courage on earth is to bear defaet without losing heart.

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2022/6/24

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immutable

它是一款代替傳統拷貝方式的第三方庫

優勢:

• 在新對象上操作不會影響原對象的數據
• 性能好

安裝使用

1.下載 npm i immutable

2.導入 import {Map} from 'immutable'

Map

語法:Map(對象)

賦值:set("屬性名","新值")

取值:get("屬性名")

toJS()轉回普通對象

import React, {
     Component } from 'react';
/** * 1.下載 npm i immutable * 2.導入 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('屬性')獲取值
console.log(objImmu.get("name"),newobjImmu.get("name"));

//toJS轉回普通對象
console.log(objImmu.toJS(),newobjImmu.toJS());
/* //寫法一 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) }) }}>修改它們的值</button> {this.state.info.get("name")}---- {this.state.info.get("age")} </div> ); } }*/
//寫法二
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()
                    })
                    
                }}>修改它們的值</button>
                {
    this.state.info.name}----
                {
    this.state.info.age}
            </div>
        );
    }
}

export default Immu02;

嵌套Map

Map中對象中的對象還要套上Map

可以通過map的get方法獲取值向組件傳值.,從而完美的解决了組件的無效刷新

shouldComponentUpdate進行判斷决定是否需要刷新

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

class Immu03 extends Component {
    
    state={
    
        info:Map({
    
            name:"碰磕",
            age:20,
            hobbit:Map({
    
                likeone:"運動",
                liketwo:"學習"
            })
        })
    }
    render() {
    
        return (
            <div>
                Immu03
                <button onClick={
    ()=>{
    this.setState({
    
                    info:this.state.info.set("name","學習啊啊啊")
                })}}>修改</button>
                {
    this.state.info.get("name")}
                <Child hobbit={
    this.state.info.get("hobbit")} ></Child> 
            </div>
        );
    }
}
class Child extends Component{
    
    shouldComponentUpdate(nextProps,nextState){
    
        //判斷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("子組件更新了");
    }
}
export default Immu03;

List

可以使用數組的屬性方法

import React, {
     Component } from 'react';
import {
    List} from 'immutable'
var arr=List([1,231,1])
let arr2=arr.push(4)//不會影響原對象結構
let arr3=arr2.concat([12,323,123])
console.log(arr,arr2,arr3);
class Immu04 extends Component {
    
    state={
    
        favor:List(['吃飯','睡覺','學習','運動'])
    }
    render() {
    
        return (
            <div>
                Immu04
                {
    
                    this.state.favor.map(item=>{
    
                        return <li key={
    item}>{
    item}</li>
                    })
                }
            </div>
        );
    }
}
export default Immu04;

實現個人修改案例

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(['睡覺','學習','敲鍵盤'])
        })
    }
    render() {
    
        return (
            <div>
                <h1>編輯個人信息</h1>
                <div>
                    <button onClick={
    ()=>{
    
                        this.setState({
    
                            info:this.state.info.set("name","愛學習").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;

通過fromJS、setIn、updateIn進行改進

• fromJS將普通對象轉換為Immutable
• setIn()深度賦值,參數一為數組形式填寫需要修改的，參數二為修改後的值
• updateIn()深度修改，參數一為數組形式填寫需要修改的，參數二為回調函數(參數為原對象)

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:['睡覺','學習','敲鍵盤']
        })
    }

    render() {
    
        return (
            <div>
                <h1>編輯個人信息</h1>
                <div>
                    <button onClick={
    ()=>{
    
                        this.setState({
    
                            info:this.state.info.setIn(["name"],"愛學習").setIn(["location","city"],"南昌")//setIn("參數一為數組","修改後的值")
                        })
                    }}>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(需要修改的對象,回調函數(參數為原對象))
                            this.setState({
    
                                info:this.state.info.updateIn(["hobbit"],(list)=>list.splice(index,1))
                            })
                        }}>删除</button></li>)
                    }
                </div>
            </div>
        );
    }
}

export default Immu06;

這樣就學費了Immutable~