目录

• module（模块）

  • Module 对象

    • module.builtinModules
    • module.createRequire(filename)
    • module.createRequireFromPath(filename)
    • module.syncBuiltinESMExports()

  • Source Map V3 的支持

    • module.findSourceMap(path[, error])

    • module.SourceMap 类

      • new SourceMap(payload)
      • sourceMap.payload
      • sourceMap.findEntry(lineNumber, columnNumber)

module（模块）#

Module 对象#

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• <Object>

当与 Module 实例（module 变量常见于 CommonJS 模块中）进行交互时，提供通用的工具方法。 通过 import 'module' 或 require('module') 访问。

module.builtinModules#

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• <string[]>

罗列 Node.js 提供的所有模块名称。可以用来判断模块是否为第三方所维护。

注意， module 在此处含义与模块封装器所提供的 module 是不同的。可以通过引入 Module 模块访问：

// module.mjs
// In an ECMAScript module
import { builtinModules as builtin } from 'module';

// module.cjs
// In a CommonJS module
const builtin = require('module').builtinModules;

module.createRequire(filename)#

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• filename <string> | <URL> 用于构造 require 函数的文件名。必须是一个文件 URL 对象、文件 URL 字符串、或绝对路径字符串。
• 返回: <require> require 函数。

import { createRequire } from 'module';
const require = createRequire(import.meta.url);

// sibling-module.js 是一个 CommonJS 模块。
const siblingModule = require('./sibling-module');

module.createRequireFromPath(filename)#

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• filename <string> Filename to be used to construct the relative require function.
• Returns: <require> Require function

const { createRequireFromPath } = require('module');
const requireUtil = createRequireFromPath('../src/utils/');

// Require `../src/utils/some-tool`
requireUtil('./some-tool');

module.syncBuiltinESMExports()#

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The module.syncBuiltinESMExports() method updates all the live bindings for builtin ES Modules to match the properties of the CommonJS exports. It does not add or remove exported names from the ES Modules.

const fs = require('fs');
const { syncBuiltinESMExports } = require('module');

fs.readFile = null;

delete fs.readFileSync;

fs.newAPI = function newAPI() {
  // ...
};

syncBuiltinESMExports();

import('fs').then((esmFS) => {
  assert.strictEqual(esmFS.readFile, null);
  assert.strictEqual('readFileSync' in fs, true);
  assert.strictEqual(esmFS.newAPI, undefined);
});

Source Map V3 的支持#

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Helpers for interacting with the source map cache. This cache is populated when source map parsing is enabled and source map include directives are found in a modules' footer.

To enable source map parsing, Node.js must be run with the flag --enable-source-maps, or with code coverage enabled by setting NODE_V8_COVERAGE=dir.

// module.mjs
// In an ECMAScript module
import { findSourceMap, SourceMap } from 'module';

// module.cjs
// In a CommonJS module
const { findSourceMap, SourceMap } = require('module');

module.findSourceMap(path[, error])#

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• path <string>
• error <Error>
• Returns: <module.SourceMap>

path is the resolved path for the file for which a corresponding source map should be fetched.

The error instance should be passed as the second parameter to findSourceMap in exceptional flows, e.g., when an overridden Error.prepareStackTrace(error, trace) is invoked. Modules are not added to the module cache until they are successfully loaded, in these cases source maps will be associated with the error instance along with the path.

module.SourceMap 类#

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new SourceMap(payload)#

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• payload <Object>

Creates a new sourceMap instance.

payload is an object with keys matching the Source map v3 format:

• file: <string>
• version: <number>
• sources: <string[]>
• sourcesContent: <string[]>
• names: <string[]>
• mappings: <string>
• sourceRoot: <string>

sourceMap.payload#

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• Returns: <Object>

Getter for the payload used to construct the SourceMap instance.

sourceMap.findEntry(lineNumber, columnNumber)#

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• lineNumber <number>
• columnNumber <number>
• Returns: <Object>

Given a line number and column number in the generated source file, returns an object representing the position in the original file. The object returned consists of the following keys:

• generatedLine: <number>
• generatedColumn: <number>
• originalSource: <string>
• originalLine: <number>
• originalColumn: <number>