1.ts环境配置
安装环境
npm install typescript -g
编译ts文件：
tsc 文件名
上面的tsc编译有点麻烦，我们可以使用自动化编译。
自动化编译：
tsc --init
根目录会生成tsconfig.json文件：
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig to read more about this file */
/* Projects */
// "incremental": true, /* Save .tsbuildinfo files to allow for incremental compilation of projects. */
// "composite": true, /* Enable constraints that allow a TypeScript project to be used with project references. */
// "tsBuildInfoFile": "./.tsbuildinfo", /* Specify the path to .tsbuildinfo incremental compilation file. */
// "disableSourceOfProjectReferenceRedirect": true, /* Disable preferring source files instead of declaration files when referencing composite projects. */
// "disableSolutionSearching": true, /* Opt a project out of multi-project reference checking when editing. */
// "disableReferencedProjectLoad": true, /* Reduce the number of projects loaded automatically by TypeScript. */
/* Language and Environment */
"target": "es2016", /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
// "lib": [], /* Specify a set of bundled library declaration files that describe the target runtime environment. */
// "jsx": "preserve", /* Specify what JSX code is generated. */
// "experimentalDecorators": true, /* Enable experimental support for legacy experimental decorators. */
// "emitDecoratorMetadata": true, /* Emit design-type metadata for decorated declarations in source files. */
// "jsxFactory": "", /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'. */
// "jsxFragmentFactory": "", /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
// "jsxImportSource": "", /* Specify module specifier used to import the JSX factory functions when using 'jsx: react-jsx*'. */
// "reactNamespace": "", /* Specify the object invoked for 'createElement'. This only applies when targeting 'react' JSX emit. */
// "noLib": true, /* Disable including any library files, including the default lib.d.ts. */
// "useDefineForClassFields": true, /* Emit ECMAScript-standard-compliant class fields. */
// "moduleDetection": "auto", /* Control what method is used to detect module-format JS files. */
/* Modules */
"module": "commonjs", /* Specify what module code is generated. */
// "rootDir": "./", /* Specify the root folder within your source files. */
// "moduleResolution": "node10", /* Specify how TypeScript looks up a file from a given module specifier. */
// "baseUrl": "./", /* Specify the base directory to resolve non-relative module names. */
// "paths": {}, /* Specify a set of entries that re-map imports to additional lookup locations. */
// "rootDirs": [], /* Allow multiple folders to be treated as one when resolving modules. */
// "typeRoots": [], /* Specify multiple folders that act like './node_modules/@types'. */
// "types": [], /* Specify type package names to be included without being referenced in a source file. */
// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
// "moduleSuffixes": [], /* List of file name suffixes to search when resolving a module. */
// "allowImportingTsExtensions": true, /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
// "resolvePackageJsonExports": true, /* Use the package.json 'exports' field when resolving package imports. */
// "resolvePackageJsonImports": true, /* Use the package.json 'imports' field when resolving imports. */
// "customConditions": [], /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
// "noUncheckedSideEffectImports": true, /* Check side effect imports. */
// "resolveJsonModule": true, /* Enable importing .json files. */
// "allowArbitraryExtensions": true, /* Enable importing files with any extension, provided a declaration file is present. */
// "noResolve": true, /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
/* JavaScript Support */
// "allowJs": true, /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */
// "checkJs": true, /* Enable error reporting in type-checked JavaScript files. */
// "maxNodeModuleJsDepth": 1, /* Specify the maximum folder depth used for checking JavaScript files from 'node_modules'. Only applicable with 'allowJs'. */
/* Emit */
// "declaration": true, /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
// "declarationMap": true, /* Create sourcemaps for d.ts files. */
// "emitDeclarationOnly": true, /* Only output d.ts files and not JavaScript files. */
// "sourceMap": true, /* Create source map files for emitted JavaScript files. */
// "inlineSourceMap": true, /* Include sourcemap files inside the emitted JavaScript. */
// "noEmit": true, /* Disable emitting files from a compilation. */
// "outFile": "./", /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
// "outDir": "./", /* Specify an output folder for all emitted files. */
// "removeComments": true, /* Disable emitting comments. */
// "importHelpers": true, /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
// "downlevelIteration": true, /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
// "sourceRoot": "", /* Specify the root path for debuggers to find the reference source code. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSources": true, /* Include source code in the sourcemaps inside the emitted JavaScript. */
// "emitBOM": true, /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
// "newLine": "crlf", /* Set the newline character for emitting files. */
// "stripInternal": true, /* Disable emitting declarations that have '@internal' in their JSDoc comments. */
// "noEmitHelpers": true, /* Disable generating custom helper functions like '__extends' in compiled output. */
// "noEmitOnError": true, /* Disable emitting files if any type checking errors are reported. */
// "preserveConstEnums": true, /* Disable erasing 'const enum' declarations in generated code. */
// "declarationDir": "./", /* Specify the output directory for generated declaration files. */
/* Interop Constraints */
// "isolatedModules": true, /* Ensure that each file can be safely transpiled without relying on other imports. */
// "verbatimModuleSyntax": true, /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
// "isolatedDeclarations": true, /* Require sufficient annotation on exports so other tools can trivially generate declaration files. */
// "allowSyntheticDefaultImports": true, /* Allow 'import x from y' when a module doesn't have a default export. */
"esModuleInterop": true, /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
// "preserveSymlinks": true, /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
"forceConsistentCasingInFileNames": true, /* Ensure that casing is correct in imports. */
/* Type Checking */
"strict": true, /* Enable all strict type-checking options. */
// "noImplicitAny": true, /* Enable error reporting for expressions and declarations with an implied 'any' type. */
// "strictNullChecks": true, /* When type checking, take into account 'null' and 'undefined'. */
// "strictFunctionTypes": true, /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
// "strictBindCallApply": true, /* Check that the arguments for 'bind', 'call', and 'apply' methods match the original function. */
// "strictPropertyInitialization": true, /* Check for class properties that are declared but not set in the constructor. */
// "strictBuiltinIteratorReturn": true, /* Built-in iterators are instantiated with a 'TReturn' type of 'undefined' instead of 'any'. */
// "noImplicitThis": true, /* Enable error reporting when 'this' is given the type 'any'. */
// "useUnknownInCatchVariables": true, /* Default catch clause variables as 'unknown' instead of 'any'. */
// "alwaysStrict": true, /* Ensure 'use strict' is always emitted. */
// "noUnusedLocals": true, /* Enable error reporting when local variables aren't read. */
// "noUnusedParameters": true, /* Raise an error when a function parameter isn't read. */
// "exactOptionalPropertyTypes": true, /* Interpret optional property types as written, rather than adding 'undefined'. */
// "noImplicitReturns": true, /* Enable error reporting for codepaths that do not explicitly return in a function. */
// "noFallthroughCasesInSwitch": true, /* Enable error reporting for fallthrough cases in switch statements. */
// "noUncheckedIndexedAccess": true, /* Add 'undefined' to a type when accessed using an index. */
// "noImplicitOverride": true, /* Ensure overriding members in derived classes are marked with an override modifier. */
// "noPropertyAccessFromIndexSignature": true, /* Enforces using indexed accessors for keys declared using an indexed type. */
// "allowUnusedLabels": true, /* Disable error reporting for unused labels. */
// "allowUnreachableCode": true, /* Disable error reporting for unreachable code. */
/* Completeness */
// "skipDefaultLibCheck": true, /* Skip type checking .d.ts files that are included with TypeScript. */
"skipLibCheck": true /* Skip type checking all .d.ts files. */
}
}
对ts文件进行监视：
监视某个ts文件
tsc --watch 文件名
监视所有ts文件
tsc --watch
当ts文件出现错误的时候不要编译：
在tsconfig.json中这样配置：
"noEmitOnError": true,
2.函数
函数参数类型声明：
function add(a: number, b: number):number {
return a+b
}
console.log(add(20,30))
3.类型推断
注意，ts更推荐创建一个变量的时候就给一个默认值，这个时候就不用指定类型了，ts可以自动推断。
推荐写法：
let a = 'hello'
console.log(a)
不推荐写法：
let a:string = 'hello'
console.log(a)
代码中:string是冗余的。
当暂时没办法确定变量的初始值，这个时候可以指定类型：
let a: string
a = 'hello'
console.log(a)
4.String和string的区别
大的String是包装对象，一般不推荐使用这个。
let str1: String //TS官方推荐的写法
str1 = new String('hello')
// 要用valueOf()来取里面的值，很玛法
console.log(str1.valueOf());
所以更推荐使用小写string，包括number，都要使用小写。
5.any任意类型
一旦把变量的类型设置成any，就意味着放弃了对该变量的类型检查。
let a: any
a = 'hello'
a = 12
// 下面这样写也是any
let b
any类型的变量可以赋值给任何类型的变量
let a: any
a = 'hello'
a = false
let str: string
str = a
// str的类型已经变成Boolean
console.log(typeof(str))
所以使用any的时候需要注意。
6.unknown未知类型
官网链接：www.typescriptlang.org/docs/handbo…
可以理解为类型安全的any。
let a: unknown
a = 99
a = false
let str: string
// 这里报错，需要使用断言的方式赋值
// str = a
str = a as string
// 或者
str = <string>a
7.void
官网链接：www.typescriptlang.org/docs/handbo…
8.never
官网链接：www.typescriptlang.org/docs/handbo…
9.object和Object
let a: object // a能存储的类型都是非原始类型，在开发中用的很少
let b: Object // b能存储的类型都是可以调用到Object方法的类型，在开发中很少使用
b = {}
b = { name: 'akbar' }
这两种对象开发中很少使用，那么在开发中用什么呢？
10.声明对象类型
let Person: {
name: string,
age?: number
}
Person = {
name: 'akbar',
age: 18
}
使用标签索引：
当我们新增某个属性的时候可以这样：
let Person: {
name: string,
age?: number,
gender?: string
}
Person = {
name: 'akbar',
age: 18,
gender: '男'
}
也可以这样写：
let Person: {
name: string,
age?: number,
gender?: string,
// 这样写的好处是可以加任何属性
[key:string]: any
}
Person = {
name: 'akbar',
age: 18,
gender: '男',
address: 'hb'
}
11.声明函数类型
let fun: (a: number, b: number) => number
//接受两个number类型的参数，并且返沪number类型的变量
fun = (a: number, b: number) => {
return a + b
}
简洁的写法：
let fun: (a: number, b: number) => number
//接受两个number类型的参数，并且返沪number类型的变量
fun = (a, b) => {
return a + b
}
12.声明数组类型
let arr: string[]
arr= ['hello','nice', 'to', 'meet', 'you']
也可以这样声明：
let arr: Array<string>
arr= ['hello','nice', 'to', 'meet', 'you']
13.tuple
注意，tuple不是关键字。
tuple里面可以存多种数据类型：
let arr: [string, number]
arr = ['akbar', 18]
也可以这样定义：
let arr: [string, ...number[]]
arr = ['akbar', 18, 34, 55]
这样可以写任意多个number类型的变量。
14.enum枚举
enum Direction {
Up,
Down,
Left,
Right
}
function walk(data: Direction) {
if (data === Direction.Up) {
console.log('向上走')
} else if (data === Direction.Down) {
console.log('向下走')
} else if (data === Direction.Left) {
console.log('想做走')
} else {
console.log('向右走')
}
}
walk(Direction.Down)
常量枚举：
const enum Direction {
Up,
Down,
Left,
Right
}
15.type
造新的类型。
type int = number
let a: int
a = 20
联合类型：
type Status = number | string
function printStatus(data: Status): void {
console.log(data)
}
printStatus(404)
printStatus('404')
又比如指定性别：
type Gender = '男' | '女'
function printGender(data: Gender): void {
console.log(data)
}
printGender('男')
printGender('女')
16.interface
interface是一种定义结构的方式。
比如：
interface IPerson {
name: string,
age: number,
address: string
}
let human: IPerson = {
name: 'akbar',
age: 23,
address: 'hb'
}
可以通过readonly来防止属性被修改：
interface IPerson {
readonly id: number,
name: string,
age?: number,
address?: string
}
let akbar: IPerson = {
id: 1,
name: 'akbar'
}
17.泛型
有时候我们需要动态的指定数据类型，这个时候可以使用泛型。
泛型函数：
function logData<T>(data: T) {
console.log(data)
}
logData<number>(34)
