Scoheart Blog

使用flow

Getting Started

yarn add flow-bin
 
npm instal flow-bin

// @flow
 
function sum(a: number, b: number) {
    return a + b;
}
 
sum(100, 200)
 
sum("1", "2")        // error

初始化配置文件

./node_modules/.bin/flow init

yarn flow init

npm exec flow init

没有安装插件的时候，只有运行时候，才会flow才会检测类型错误

./node_modules/.bin/flow
 
yarn flow
 
npm exec flow

安装插件之后，可以在vscode编码的时候直接看到错误 flow language support

最终执行的代码一定要是原始的js（不带任何flow类型注解的）

npm install flow-remove-types
 
yarn add flow-remove-types

yarn flow-remove-types demo.js -o demo_finish.js
 
npm exec
npm x
npx flow-remove-types demo.js -o demo_finish.js
 
./node_modules/.bin/flow-remove-types demo.js -o demo_finish.js
 
npm run xxxx

Primitive Type 原始类型

void 类型

const a: void = undefined;

null 类型

const obj: null = null;

string 类型

const str: string = "hello world";

number 类型

const num1: number = 22;
 
const num2: number = NaN;
 
const num3: number = Infinity;

boolean 类型

const isFalse: boolean = false;
 
const isTrue: boolean = trun;

symbol 类型

const sym: symbol = Symbol();

结构类型

Array 类型

const arr1: Array<number> = [ 1, 2, 3, 4 ];
 
const arr2: number[] = [1, 2, 3, 4];

Tuple 类型

const tuple: [string, number] = ["hello", 22];

Object 类型

const obj: {prop1: string, prop2: number} = {
	prop1: "shuhao",
	prop2: 22
}
 
const obj2: {prop1?: string, prop2: number} = {
	prop2: 22
}
 
const obj3: { [string]: "string" } = {}
obj3.key1 = "shuhao"
obj3.key1 = 22                 // error

function 类型

function fn(a: nubmer, b: number): number {
	return a + b;
}
 
function fn2():void {
	console.log("hello world");
}
 
function fn3(callback: (string, nubmer) => void): void {
	callback("hello world", 1024);
}

特殊类型

literal 字面量类型

const str: "hello" = "hello";
 
const num: 2 = 2;
 
const num: 3 = 2;           // error

联合类型

const str: "heart sco" | "zilong wang" | "tongzian zhang" = "heart sco"

V8 Untitled