TypeScript的基操
TypeScript的基本概念
TypeScript官网上是这么说的“TypeScript is JavaScript with syntax for types. ”，也就是TypeScript是带有类型语法的JavaScript。也就是JavaScript的超集。
为什么要使用TypeScript？
我们知道，JavaScript对类型没有一个强制的规定，变量的类型是“动态”调整的，这样会导致开发出的应用产生不确定的问题。
TypeScript能够在开发时对类型进行检查，在编译时对类型进行判断。
我们可以这么理解：
- JS 就像在白纸上写文章，写完后发布了，读者（用户）读到一半才发现你有错别字。
- TS 就像在 Word 里写文章，当你打错字（类型不匹配）时，红色的波浪线立刻就会提示你修改。
TypeScript的环境搭建
TypeScript 发展的如今，支持很多的搭建方式，我们可以通过tsc、babel、esbuild、vite等的方式进行搭建。这些工具都是通过将ts文件编译成 js 文件 + 类型申明文件。
tsc搭建
-
npm init创建 package.json 文件 -
添加开发依赖
"devDependencies": {
"typescript": "5.9.2"
}
- 设置开发脚本
"scripts": {
"compile": "tsc",
"compile:watch": "tsc --watch"
},
-
tsc --init自动化添加 tsconfig.json 文件。 输出的目录"outDir": "./dist
{
"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. */
// "libReplacement": true, /* Enable lib replacement. */
// "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. */
// "rewriteRelativeImportExtensions": true, /* Rewrite '.ts', '.tsx', '.mts', and '.cts' file extensions in relative import paths to their JavaScript equivalent in output files. */
// "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": "./dist", /* 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. */
// "erasableSyntaxOnly": true, /* Do not allow runtime constructs that are not part of ECMAScript. */
// "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. */
}
}
-
pnpm i安装依赖 -
创建src文件夹，在文件夹中创建
index.ts
// index.js
const a = 10;
-
命令行执行
pnpm compile进行编译 -
生成文件夹dist ，并形成
index.js文件，说明编译成功。 -
编辑
tsconfig.json文件中的"declaration": true，就能够生成类型声明文件。
// index.d.ts
declare const a = 10;
到这里基本上成功创建了ts的编译环境。在这个过程中，有几个重要的文件配置分别是：
-
package.json中的typescript依赖以及脚本命令 -
tsconfig.json中的typescript配置
babel搭建
-
npm init创建 package.json 文件 -
添加开发依赖
"devDependencies": {
"@babel/cli": "^7.28.3",
"@babel/core": "^7.28.3",
"@babel/preset-env": "^7.28.3",
"@babel/preset-typescript": "^7.27.1",
"typescript": "^5.9.2"
}
- 设置开发脚本
"scripts": {
"compile": "babel src --out-dir dist --extensions \".ts,.tsx\"",
"compile:watch": "babel src --out-dir dist --extensions \".ts,.tsx\" --watch"
},
-
tsc --init自动化添加 tsconfig.json 文件。 输出的目录"outDir": "./dist
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig to read more about this file */
/* Projects */
/* Language and Environment */
"target": "es2016", /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
/* Modules */
"module": "commonjs", /* Specify what module code is generated. */
/* Emit */
"declaration": true, /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
"esModuleInterop": true, /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
"forceConsistentCasingInFileNames": true, /* Ensure that casing is correct in imports. */
"strict": true, /* Enable all strict type-checking options. */
}
}
-
pnpm i安装依赖 - 添加 babel 的配置文件
babel.config.js
module.exports ={
presets: [
"@babel/preset-env",
"@babel/preset-typescript",
],
}
- 创建src文件夹，在文件夹中创建
index.ts
// index.js
const a = 10;
-
命令行执行
pnpm compile进行编译 -
生成文件夹dist ，并形成
index.js文件，说明编译成功。 -
babel生成类型声明文件还是需要通过
ts cli 进行，通过脚本完成。编辑tsconfig.json文件中的"declaration": true
"scripts": {
"compile:types": "tsc --emitDeclarationOnly",
"bulid": "pnpm compile && pnpm compile:typesÏ"
},
- 生成类型声明文件
index.d.js
// index.d.ts
declare const a = 10;
与tsc搭建的区别在于：
多引入一些babel的依赖。同时不能生成类型声明文件，还是需要通过 tsc 来完成。
