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babel 编译核心

var babel = require('babel-core');
import { transform } from 'babel-core';
import & as babel from 'babel-core';

1、babel.transform(code: string, options? :Object)

在code上传入转换的代码,返回一个对象包含生产的代码,sourcemap 及 ast
babel.transform(code, options) // => {code, map, ast}

输入

const babel = require("babel-core");

const result = babel.transform(
  `
  import React from "react";
  import ReactDOM from "react-dom";

  ReactDOM.render(
    

React Jsx Transform Without Webpack

, document.getElementById("root") ); `, { presets: ["react"], } ); console.log(result);

输出

{
  metadata: {
    usedHelpers: [],
    marked: [],
    modules: { imports: [Array], exports: [Object] }
  },
  options: {
    filename: 'unknown',
    filenameRelative: 'unknown',
    inputSourceMap: undefined,
    env: { development: [Object] },
    mode: undefined,
    retainLines: false,
    highlightCode: true,
    suppressDeprecationMessages: false,
    presets: [],
    plugins: [ [Array], [Array], [Array], [Array] ],
    ignore: [],
    only: undefined,
    code: true,
    metadata: true,
    ast: true,
    extends: undefined,
    comments: true,
    shouldPrintComment: undefined,
    wrapPluginVisitorMethod: undefined,
    compact: 'auto',
    minified: false,
    sourceMap: undefined,
    sourceMaps: undefined,
    sourceMapTarget: 'unknown',
    sourceFileName: 'unknown',
    sourceRoot: undefined,
    babelrc: true,
    sourceType: 'module',
    auxiliaryCommentBefore: undefined,
    auxiliaryCommentAfter: undefined,
    resolveModuleSource: undefined,
    getModuleId: undefined,
    moduleRoot: undefined,
    moduleIds: false,
    moduleId: undefined,
    passPerPreset: false,
    parserOpts: false,
    generatorOpts: false,
    basename: 'unknown'
  },
  ignored: false,
  code: '\n' +
    'import React from "react";\n' +
    'import ReactDOM from "react-dom";\n' +
    '\n' +
    'ReactDOM.render(React.createElement(\n' +
    '  "h3",\n' +
    '  null,\n' +
    '  "React Jsx Transform Without Webpack"\n' +
    '), document.getElementById("root"));',
  ast: Node {
    type: 'File',
    start: 0,
    end: 177,
    loc: SourceLocation { start: [Position], end: [Position] },
    program: Node {
      type: 'Program',
      start: 0,
      end: 177,
      loc: [SourceLocation],
      sourceType: 'module',
      body: [Array],
      directives: []
    },
    comments: [],
    tokens: [
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token]
    ]
  },
  map: null
}

2、babel.transformFile(filename: string, options?: Object, callback:Function)

异步方式转换一整个文件

输入

const fileResult = babel.transformFile(
  "./index.jsx",
  {
    presets: ["react"],
  },
  function (err, result) {
    console.log(err, result);
  }
);

console.log("fileResult", fileResult);

输出

null {
  metadata: {
    usedHelpers: [],
    marked: [],
    modules: { imports: [Array], exports: [Object] }
  },
  options: {
    filename: './index.jsx',
    filenameRelative: './index.jsx',
    inputSourceMap: undefined,
    env: { development: [Object] },
    mode: undefined,
    retainLines: false,
    highlightCode: true,
    suppressDeprecationMessages: false,
    presets: [],
    plugins: [
      [Array], [Array],
      [Array], [Array],
      [Array], [Array],
      [Array], [Array]
    ],
    ignore: [],
    only: undefined,
    code: true,
    metadata: true,
    ast: true,
    extends: undefined,
    comments: true,
    shouldPrintComment: undefined,
    wrapPluginVisitorMethod: undefined,
    compact: 'auto',
    minified: false,
    sourceMap: undefined,
    sourceMaps: undefined,
    sourceMapTarget: 'index.jsx',
    sourceFileName: 'index.jsx',
    sourceRoot: undefined,
    babelrc: true,
    sourceType: 'module',
    auxiliaryCommentBefore: undefined,
    auxiliaryCommentAfter: undefined,
    resolveModuleSource: undefined,
    getModuleId: undefined,
    moduleRoot: undefined,
    moduleIds: false,
    moduleId: undefined,
    passPerPreset: false,
    parserOpts: false,
    generatorOpts: false,
    basename: 'index'
  },
  ignored: false,
  code: 'import React from "react";\n' +
    'import ReactDOM from "react-dom";\n' +
    '\n' +
    'ReactDOM.render(React.createElement(\n' +
    '  "h3",\n' +
    '  null,\n' +
    '  "React Jsx Transform Without Webpack"\n' +
    '), document.getElementById("root"));',
  ast: Node {
    type: 'File',
    start: 0,
    end: 164,
    loc: SourceLocation { start: [Position], end: [Position] },
    program: Node {
      type: 'Program',
      start: 0,
      end: 164,
      loc: [SourceLocation],
      sourceType: 'module',
      body: [Array],
      directives: []
    },
    comments: [],
    tokens: [
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token],
      [Token], [Token], [Token], [Token]
    ]
  },
  map: null
}

3、babel.transformFileSync(filename: string, opitons?: Object)

同步方式转换一整个文件
const astResult = babel.transformFromAst("./index.jsx", {
  presets: ["react"],
});

4、babel.transformFromAst(ast: Object, code?: string, options?: Object)

给出一个AST,转换它
const originCode = "function getName() {}";
console.log("originCode", originCode);
const originAst = babylon.parse(originCode, {
  allowReturnOutsideFunction: true,
});
console.log("originAst", originAst);
const { code, map, ast } = babel.transformFromAst(originAst, originCode);

console.log("code", code);
console.log("map", map);
console.log("ast", ast);
babylon 网站工具转换的AST
{
  "type": "Program",
  "start": 0,
  "end": 16,
  "body": [
    {
      "type": "IfStatement",
      "start": 0,
      "end": 16,
      "test": {
        "type": "Literal",
        "start": 3,
        "end": 7,
        "value": true,
        "raw": "true"
      },
      "consequent": {
        "type": "ReturnStatement",
        "start": 9,
        "end": 16,
        "argument": null
      },
      "alternate": null
    }
  ],
  "sourceType": "module"
}
const originAst = babylon.parse(originCode, {
  allowReturnOutsideFunction: true,
});
originAst结果
Node {
  type: 'File',
  start: 0,
  end: 16,
  loc: SourceLocation {
    start: Position { line: 1, column: 0 },
    end: Position { line: 1, column: 16 }
  },
  program: Node {
    type: 'Program',
    start: 0,
    end: 16,
    loc: SourceLocation { start: [Position], end: [Position] },
    sourceType: 'script',
    body: [ [Node] ],
    directives: []
  },
  comments: [],
  tokens: [
    Token {
      type: [KeywordTokenType],
      value: 'if',
      start: 0,
      end: 2,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 2,
      end: 3,
      loc: [SourceLocation]
    },
    Token {
      type: [KeywordTokenType],
      value: 'true',
      start: 3,
      end: 7,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 7,
      end: 8,
      loc: [SourceLocation]
    },
    Token {
      type: [KeywordTokenType],
      value: 'return',
      start: 9,
      end: 15,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 15,
      end: 16,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 16,
      end: 16,
      loc: [SourceLocation]
    }
  ]
}
const { code, map, ast } = babel.transformFromAst(originAst, originCode);
// code
if (true) return;
// map
null
// ast
 Node {
  type: 'File',
  start: 0,
  end: 16,
  loc: SourceLocation {
    start: Position { line: 1, column: 0 },
    end: Position { line: 1, column: 16 }
  },
  program: Node {
    type: 'Program',
    start: 0,
    end: 16,
    loc: SourceLocation { start: [Position], end: [Position] },
    sourceType: 'script',
    body: [ [Node] ],
    directives: []
  },
  comments: [],
  tokens: [
    Token {
      type: [KeywordTokenType],
      value: 'if',
      start: 0,
      end: 2,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 2,
      end: 3,
      loc: [SourceLocation]
    },
    Token {
      type: [KeywordTokenType],
      value: 'true',
      start: 3,
      end: 7,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 7,
      end: 8,
      loc: [SourceLocation]
    },
    Token {
      type: [KeywordTokenType],
      value: 'return',
      start: 9,
      end: 15,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 15,
      end: 16,
      loc: [SourceLocation]
    },
    Token {
      type: [TokenType],
      value: undefined,
      start: 16,
      end: 16,
      loc: [SourceLocation]
    }
  ]
}

options

Babel CLI
你可以通过Babel CLI 这样传递Options的参数
babel --name=value

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