编译选项
https://www.typescriptlang.org/tsconfig
TypeScript 提供了非常多的编译选项,这一章会详细介绍每一个选项的作用,并给出对应的示例。
索引(点击选项跳转到详细介绍):
选项 | 类型 | 默认值 | 描述 |
---|---|---|---|
allowJs | boolean | false | 允许编译 js 文件 |
allowSyntheticDefaultImports | boolean | false | 允许对不包含默认导出的模块使用默认导入。这个选项不会影响生成的代码,只会影响类型检查。 |
allowJs
允许编译 js 文件。
设置为 true
时,js 文件会被 tsc 编译,否则不会。一般在项目中 js, ts 混合开发时需要设置。
# 设置为 true 时,编译后的文件包含 foo.js
├── lib
│ ├── foo.js
│ └── index.js
├── src
│ ├── foo.js
│ └── index.ts
├── package.json
└── tsconfig.json
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# 设置为 false 时,编译后的文件不包含 foo.js
├── lib
│ └── index.js
├── src
│ ├── foo.js
│ └── index.ts
├── package.json
└── tsconfig.json
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allowSyntheticDefaultImports
允许对不包含默认导出的模块使用默认导入。这个选项不会影响生成的代码,只会影响类型检查。
export = foo
是 ts 为了兼容 commonjs 创造的语法,它对应于 commonjs 中的 module.exports = foo
。
在 ts 中,如果要引入一个通过 export = foo
导出的模块,标准的语法是 import foo = require('foo')
,或者 import * as foo from 'foo'
。
但由于历史原因,我们已经习惯了使用 import foo from 'foo'
。
这个选项就是为了解决这个问题。当它设置为 true
时,允许使用 import foo from 'foo'
来导入一个通过 export = foo
导出的模块。当它设置为 false
时,则不允许,会报错。
当然,我们一般不会在 ts 文件中使用 export = foo
来导出模块,而是在写(符合 commonjs 规范的)第三方库的声明文件时,才会用到 export = foo
来导出类型。
比如 React 的声明文件中,就是通过 export = React
来导出类型:
export = React;
export as namespace React;
declare namespace React {
// 声明 React 的类型
}
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此时若我们通过 import React from 'react'
来导入 react 则会报错,查看示例 :
import React from 'react';
// Module '"typescript-tutorial/examples/compiler-options/02-allowSyntheticDefaultImports/false/node_modules/@types/react/index"' can only be default-imported using the 'esModuleInterop' flagts(1259)
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解决办法就是将 allowSyntheticDefaultImports
设置为 true
。
完整配置
Details
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */
/* Projects */
// "incremental": true, /* Enable incremental compilation */
// "composite": true, /* Enable constraints that allow a TypeScript project to be used with project references. */
// "tsBuildInfoFile": "./", /* Specify the folder for .tsbuildinfo incremental compilation files. */
// "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": "es6",
/* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
"lib": [
"WebWorker",
"es6",
"dom",
"DOM",
"DOM.Iterable"
],
/* 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 TC39 stage 2 draft 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. */
/* Modules */
"module": "commonjs",
/* Specify what module code is generated. */
// "rootDir": "./", /* Specify the root folder within your source files. */
"moduleResolution": "node", /* 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. */
"resolveJsonModule": true, /* Enable importing .json files */
// "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. */
// "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": "./dist",
/* Specify an output folder for all emitted files. */
"removeComments": true, /* Disable emitting comments. */
// "noEmit": true, /* Disable emitting files from a compilation. */
// "importHelpers": true, /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
// "importsNotUsedAsValues": "remove", /* Specify emit/checking behavior for imports that are only used for types */
// "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. */
// "inlineSourceMap": true, /* Include sourcemap files inside the emitted JavaScript. */
// "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. */
// "preserveValueImports": true, /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
/* Interop Constraints */
// "isolatedModules": true, /* Ensure that each file can be safely transpiled without relying on other imports. */
"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": false, /* 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. */
// "noImplicitThis": true, /* Enable error reporting when `this` is given the type `any`. */
// "useUnknownInCatchVariables": true, /* Type catch clause variables as 'unknown' instead of 'any'. */
"alwaysStrict": true,
/* Ensure 'use strict' is always emitted. */
// "noUnusedLocals": true, /* Enable error reporting when a 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, /* Include 'undefined' in index signature results */
// "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. */
},
"ts-node": {
"preferTsExts": true,
"transpileOnly": true
},
"include": [
"src/**/*"
],
"exclude": [
"node_modules"
]
}
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