TypeScript泛型参数默认类型和新的strict编译选项

目录

• 概述
• 为组件类创建类型定义
• 使用泛型类型定义 Props 和 State
• 泛型参数默认类型
• 其它事例
• 新的--strict主要编译选项

• 改进的--init输出
• --checkJS选项下.js文件中的错误

class Greeting extends react.Component {
  render() {
    return <span>Hello, {this.props.name}!</span>;
  }
}

declare namespace React {
  class Component {
    props: any;
    state: any;
  }
}

class Greeting extends React.Component {
  render() {
    return <span>Hello, {this.props.name}!</span>
  }
}

<Greeting name="world" />

<span>Hello, World!</span>

declare namespace React {
  class Component <Props, State> {
    props: Props;
    state: State;
  }
}

type GreetingProps = { name: string };
class Greeting extends React.Component<GreetingProps, any> {
  render() {
    return <span>Hello, {this.props.name}!</span>;
  }
}

// Error: 泛型类型 Component<Props, State>
// 需要 2 个类型参数。
class Greeting extends React.Component {
  render() {
    return <span>Hello, {this.props.name}!</span>;
  }
}

class Greeting extends React.Component<any, any> {
  render() {
    return <span>Hello, {this.props.name}!</span>;
  }
}

declare namespace React {
  class Component<Props = any, State = any> {
    props: Props;
    state: State;
  }
}

class Greeting extends React.Component {
  render() {
    return <span>Hello, {this.props.name}!</span>;
  }
}

type GreetingProps = { name: string };
class Greeting extends React.Component<GreetingProps, any> {
  render() {
    return <span>Hello, {this.props.name}!</span>;
  }
}

class Greeting extends React.Component<GreetingProps> {
  render() {
    return <span>Hello, {this.props.name}!</span>;
  }
}

type constructor<T> = new (...args: any[]) => T;
type constructable = Constructor<{}>;

type Constructor<T = {}> = new (...args: any[]) => T;

{
  "strict": true,
  "alwaysStrict": false
}

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', or 'ESNEXT'. */
    "module": "commonjs",                     /* Specify module code generation: 'commonjs', 'amd', 'system', 'umd' or 'es2015'. */
    // "lib": [],                             /* Specify library files to be included in the compilation:  */
    // "allowJs": true,                       /* Allow JavaScript files to be compiled. */
    // "checkJs": true,                       /* Report errors in .js files. */
    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    // "outDir": "./",                        /* Redirect output structure to the directory. */
    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    // "removeComments": true,                /* Do not emit comments to output. */
    // "noEmit": true,                        /* Do not emit outputs. */
    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
    /* Strict Type-Checking Options */
    "strict": true                            /* Enable all strict type-checking options. */
    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
    // "strictNullChecks": true,              /* Enable strict null checks. */
    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
    /* Additional Checks */
    // "noUnusedLocals": true,                /* Report errors on unused locals. */
    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
    /* Module Resolution Options */
    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    // "types": [],                           /* Type declaration files to be included in compilation. */
    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
    /* Source Map Options */
    // "sourceRoot": "./",                    /* Specify the location where debugger should locate TypeScript files instead of source locations. */
    // "mapRoot": "./",                       /* Specify the location where debugger should locate map files instead of generated locations. */
    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
    /* Experimental Options */
    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
  }
}