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Typescript的使用

2022-03-28 16:32 155 查看 https://www.cnblogs.com/cnroad

前期准备

#安装一些全局的npm包

# 安装yarn包,用于管理安装npm包
npm i yarn -g

# 安装typescript包, 用于学习typescript
npm i typescript -g

# 安装ts-node包,用于直观了解运行typescript文件后的结果
npm i ts-node -g

项目初始化

#创建项目文件夹并进入
mkdir ts-init && cd ts-init

#yarn初始化项目, -y表示不需要确认,直接按默认的来
yarn init -y

#typescript初始化项目, 全局安装typescript包后,有个tsc命令
tsc --init

#安装typescript npm包到本地, 如果你全局安装过typescript,这一步可以略过
yarn add typescript -D

package.json
文件是
yarn
初始化创建的,这里script脚本是一些命令, 例如执行
yarn dev
它表示用
ts-node
命令运行
index.ts
文件,
yarn build
表示用
tsc
命令编译项目文件下的ts文件,
yarn watch
表示监听项目文件下ts文件的变化并做出编译。

{
"name": "ts-init",
"version": "1.0.0",
"main": "index.js",
"license": "MIT",
"scripts": {
"dev": "ts-node index.js",
"build": "tsc",
"watch": "tsc -w"
},
"dependencies": {},
"devDependencies": {
"typescript": "^4.6.3"
}
}

tsconfig.json
这个文件是
tsc
初始化
typescirpt
项目所创建的文件,包含了一些配置信息

{
"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": "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 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. */
// "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": 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. */
}
}

举个例子

这里创建了一个演示用的foo函数,接收一个字符串参数bar,返回一个字符串结果。请分别用

package.json
里的命令来动手试一试看一看结果吧

/**
*
* @param {string} bar
* @return {string}
*/
function foo(bar: string): string {
return `hello, ${bar}`;
}

console.log(foo('ataola'))
console.log(foo('world'))

项目文件地址: https://gitee.com/taoge2021/study-typescript/tree/master/base/ts-init

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