TS编译选项
# TS编译选项
今天我们主要来学习TS的编译选项
# 编译TS
# 自动编译文件
编译文件时，使用 -w 指令后，TS编译器会自动监视文件的变化，并在文件发生变化时对文件进行重新编译。
tsc xxx.ts -w
一个文件一个文件的编译太麻烦了，我们可以对整个项目进行编译
# 自动编译整个项目
首先在项目根目录下创建一个ts的配置文件 tsconfig.json，然后就可以使用tsc指令，编译项目下的所有ts文件为js文件，当然也可以开启监视模式tsc -w监视所有的文件
我们使用 tsc --init 可以初始化一个tsconfig.json文件，通过对配置文件的设置可以进行自定义的ts编译
{
"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": "es5", /* 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 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": "./", /* 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. */
/* 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": 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. */
// "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. */
}
}
下面我们在介绍tsconfig.json文件中的一些配置选项
# 配置选项
总览
{
"compilerOptions": {
"target": "es5", // 指定 ECMAScript 目标版本: 'ES5'
"module": "commonjs", // 指定使用模块: 'commonjs', 'amd', 'system', 'umd' or 'es2015'
"moduleResolution": "node", // 选择模块解析策略
"experimentalDecorators": true, // 启用实验性的ES装饰器
"allowSyntheticDefaultImports": true, // 允许从没有设置默认导出的模块中默认导入。
"sourceMap": true, // 把 ts 文件编译成 js 文件的时候，同时生成对应的 map 文件
"strict": true, // 启用所有严格类型检查选项
"noImplicitAny": true, // 在表达式和声明上有隐含的 any类型时报错
"alwaysStrict": true, // 以严格模式检查模块，并在每个文件里加入 'use strict'
"declaration": true, // 生成相应的.d.ts文件
"removeComments": true, // 删除编译后的所有的注释
"noImplicitReturns": true, // 不是函数的所有返回路径都有返回值时报错
"importHelpers": true, // 从 tslib 导入辅助工具函数
"lib": ["es6", "dom"], // 指定要包含在编译中的库文件
"typeRoots": ["node_modules/@types"],
"outDir": "./dist", // 编译结果输出目录
"rootDir": "./src" // 源代码ts所在目录
},
"include": [
"./src/**/*.ts"
],
"exclude": [
"node_modules",
"dist",
"**/*.test.ts",
]
}
# ① include
重要
是一个数组，用来指定需要编译的ts文件，其中
*表示任意文件**表示任意目录默认值：
["**/*"]
"include":["src/**/*", "test/**/*"] // 所有src目录和test目录下的文件都会被编译
# ② exclude
定义不需要被编译的文件目录
默认值：
["node_modules", "bower_components", "jspm_packages"]
"exclude": ["./src/hello/**/*"] // src下hello目录下的文件都不会被编译
# ③ extends
- 定义被继承的配置文件
"extends": "./configs/base" // 当前配置文件中会自动包含config目录下base.json中的所有配置信息
# ④ files
- 指定被编译文件的列表，只有需要编译的文件少时才会用到
"files": [
"core.ts",
"sys.ts",
"types.ts",
"scanner.ts",
"parser.ts",
"utilities.ts",
"binder.ts",
"checker.ts",
"tsc.ts"
]
- 列表中的文件都会被TS编译器所编译
# ⑤ compilerOptions
重要 编译选项，在compilerOptions中包含多个子选项，用来完成对编译的配置
对于这些选项有哪些可选值，我们可以随便写一个值，编辑器会提示我们有哪些可选值
# ① target
设置ts代码编译的目标版本
可选值： "ES3"（默认）, "ES5", "ES6", "ES2015", "ES2016", "ES2017", "ES2018", "ES2019", "ES2020", "ES2021", "ESNext".
"compilerOptions": {
"target": "ES6"
}
- 如上设置，我们所编写的ts代码将会被编译为ES6版本的js代码
# ② lib
指定代码运行时所包含的库（宿主环境）
可选值："ES5", "ES6", "ES2015", "ES2015.Collection", "ES2015.Iterable", "ES2015.Promise", "DOM", "DOM.Iterable", "ScriptHost", "WebWorker", "WebWorker.ImportScripts"......
"compilerOptions": {
"lib": ["ES6", "DOM"]
}
一般来说，如果是运行在浏览器环境下的，就不需要自己单独设置这个
# ③ module
设置编译后代码使用的模块化系统
可选值："CommonJS", "AMD", "System", "UMD", "ES6", "ES2015", "ES2020", "ESNext", "None", "es2022", "node12", "nodenext"
"compilerOptions": {
"module": "CommonJS"
}
# ④ outDir
编译后文件的所在目录
默认情况下，编译后的js文件会和ts文件位于相同的目录，设置outDir后可以改变编译后文件的位置
"compilerOptions": {
"outDir": "./dist"
}
- 设置后编译后的js文件将会生成到dist目录。可以将源码与编译后的代码分开存放
# ⑤ outFile
将所有的文件编译为
一个js文件默认会将所有的编写在全局作用域中的代码合并为一个js文件，如果 module 制定了 None、System 或 AMD 则会将模块一起合并到文件之中
"compilerOptions": {
"outFile": "./dist/app.js"
}
这种合并，我们应该交给打包工具去做，我们后面会说
# ⑥ rootDir
- 指定代码的根目录，默认情况下编译后文件的目录结构会以最长的公共目录为根目录，通过rootDir可以手动指定根目录
"compilerOptions": {
"rootDir": "./src"
}
# ⑦ 其他配置
| 标题 | 功能 |
|---|---|
| allowJs | 是否对js文件编译，默认值：false |
| checkJs | 是否对js文件进行语法检查，默认值：false |
| removeComments | 是否删除注释，默认值：false |
| noEmit | 不生成编译后的文件，默认值：false |
| noEmitOnError | 当有错误的时候不生成编译后的文件，默认值：false |
| sourceMap | 是否生成sourceMap，默认值：false |
# ⑧ 严格检查
| 标题 | 功能 |
|---|---|
| strict | 启用所有的严格检查，设置后相当于开启了所有的严格检查，默认值：false |
| alwaysStrict | 总是以严格模式对代码进行编译，默认值：false |
| noImplicitAny | 禁止隐式的any类型，默认值：false |
| noImplicitThis | 禁止类型不明确的this，默认值：false |
| strictBindCallApply | 严格检查bind、call和apply的参数列表，默认值：false |
| strictFunctionTypes | 严格检查函数的类型，默认值：false |
| strictNullChecks | 严格的空值检查，默认值：false |
| strictPropertyInitialization | 严格检查属性是否初始化，默认值：false |
# ⑨ 额外检查
| 标题 | 功能 |
|---|---|
| noFallthroughCasesInSwitch | 检查switch语句包含正确的break |
| noImplicitReturns | 检查函数没有隐式的返回值 |
| noUnusedLocals | 检查未使用的局部变量 |
| noUnusedParameters | 检查未使用的参数 |
| allowUnreachableCode | 检查不可达代码；true：忽略不可达代码，false：不可达代码将引起错误 |
| noEmitOnError | 有错误的情况下不进行编译，默认值：false |