TypeScript+react+webpack

因为接下来的项目，需要用到TypeScript，总结一下学习内容

1、Installing TypeScript

 npm install -g typescript

2、build ts file

tsc **.ts

3、type annotations

在ts中，必须要定义变量的类型，主要有：

boolean: let isdone:boolean=false

number: let num:number =6 / 0xf00d / 0b1010 / 0o744

string:let s:string='test'

Array:let list:Array=[1,2,3].

Tuple:let x:[String,number]=['a',1]

Enum:enum Color {Red,Green,Blue} let c:Color=Color.Green

Any:let notSure:any=4  noteSure="test" notSure=false

void: function fun():void{consolt.log('test')}

null and undefined:let u:undefined=u:undefined      let n:null=null

never：

// Function returning never must have unreachable end point
function error(message: string): never {
    throw new Error(message);
}

// Inferred return type is never
function fail() {
    return error("Something failed");
}

// Function returning never must have unreachable end point
function infiniteLoop(): never {
    while (true) {
    }
}

Object :represents the non-primitive type, i.e. anything that is not number, string, boolean, bigint, symbol, null, or undefined:

Type assertions：Type assertions have two forms. One is the “angle-bracket” syntax:

let someValue: any = "this is a string";

let strLength: number = (someValue).length;

And the other is the as-syntax:

let someValue: any = "this is a string";

let strLength: number = (someValue as string).length;

 两种方式都可以：但是如果要是要转换为JSX的话，只能用as

 

4、How to wire up typescript with react and webpack

1)新建项目

mkdir proj
cd proj
mkdir src
cd src
mkdir components
cd ..

the strcture like this:

proj/
├─ dist/
└─ src/
   └─ components/

webpack 可以自动生成dist文件夹

2)初始化项目

npm init -y

创建package.json

3)安装依赖

npm install --save-dev webpack webpack-cli
npm install --save react react-dom
npm install --save-dev @types/react @types/react-dom
//let ts and webpack play well together
npm install --save-dev typescript ts-loader source-map-loader  

 4)添加typescript配置文件：learn more about tsconfig.json

{
    "compilerOptions": {
        "outDir": "./dist/",
        "sourceMap": true,
        "noImplicitAny": true,
        "module": "commonjs",
        "target": "es6",
        "jsx": "react"
    }
}

5)开始写功能

create a file named hello.tsx in src/components

import * as React from "react";

export interface HelloProps { compiler: string; framework: string; }

export const Hello = (props: HelloProps) => 
Hello from {props.compiler} and {props.framework}!
;

 或者：

import * as React from "react";

export interface HelloProps { compiler: string; framework: string; }

// 'HelloProps' describes the shape of props.
// State is never set so we use the '{}' type.
export class Hello extends React.Component {
    render() {
        return 
Hello from {this.props.compiler} and {this.props.framework}!
;
    }
}

 Then create an index.tsx in src

import * as React from "react";
import * as ReactDOM from "react-dom";

import { Hello } from "./components/Hello";

ReactDOM.render(
    ,
    document.getElementById("example")
);

create a file at the root of proj named index.html

6)create webpack configuration:webpack.config.js

module.exports = {
    mode: "production",

    // Enable sourcemaps for debugging webpack's output.
    devtool: "source-map",

    resolve: {
        // Add '.ts' and '.tsx' as resolvable extensions.
        extensions: [".ts", ".tsx"]
    },

    module: {
        rules: [
            {
                test: /\.ts(x?)$/,
                exclude: /node_modules/,
                use: [
                    {
                        loader: "ts-loader"
                    }
                ]
            },
            // All output '.js' files will have any sourcemaps re-processed by 'source-map-loader'.
            {
                enforce: "pre",
                test: /\.js$/,
                loader: "source-map-loader"
            }
        ]
    },

    // When importing a module whose path matches one of the following, just
    // assume a corresponding global variable exists and use that instead.
    // This is important because it allows us to avoid bundling all of our
    // dependencies, which allows browsers to cache those libraries between builds.
    externals: {
        "react": "React",
        "react-dom": "ReactDOM"
    }
};

 

npx webpack