[后端节点js文件中未定义请求错误

Question

我的nodejs js文件在CLI nodejs上下文中执行时引发错误“ ReferenceError：未定义”。但是，在nodejs REPL交互式shell中执行“ console.log（require）”将返回有效的函数定义。

$ cat r.js
console.log(require);

$ node
Welcome to Node.js v12.17.0.
Type ".help" for more information.
> console.log(require);
[Function: require] {
  resolve: [Function: resolve] { paths: [Function: paths] },
  main: undefined,
  extensions: [Object: null prototype] {
    '.js': [Function],
    '.json': [Function],
    '.node': [Function]
  },
  cache: [Object: null prototype] {}
}
undefined

$ node r.js
(node:8341) ExperimentalWarning: The ESM module loader is experimental.
file:///work/testnodejs/r.js:1
console.log(require);
        ^

ReferenceError: require is not defined
    at file:///work/testnodejs/r.js:1:13

Answer 1

在节点的REPL下执行console.log（需要）。>>

> console.log(require);
[Function: require] {
  resolve: [Function: resolve] { paths: [Function: paths] },
  main: undefined,
  extensions: [Object: null prototype] {
    '.js': [Function],
    '.json': [Function],
    '.node': [Function]
  },
  cache: [Object: null prototype] {}
}
undefined
在CLI nodejs上下文中执行（仅使用一条语句console.log（require）;）

node helloWorld.js
Function: require] {
  resolve: [Function: resolve] { paths: [Function: paths] },
  main: Module {
    id: '.',
    path: '/Applications/node-course',
    exports: {},
    parent: null,
    filename: '/Applications/node-course/helloWorld.js',
    loaded: false,
    children: [],
    paths: [
      '/Applications/node-course/node_modules',
      '/Applications/node_modules',
      '/node_modules'
    ]
  },
  extensions: [Object: null prototype] {
    '.js': [Function],
    '.json': [Function],
    '.node': [Function]
  },
  cache: [Object: null prototype] {
    '/Applications/node-course/helloWorld.js': Module {
      id: '.',
      path: '/Applications/node-course',
      exports: {},
      parent: null,
      filename: '/Applications/node-course/helloWorld.js',
      loaded: false,
      children: [],
      paths: [Array]
    }
  }
}
require是Node.js中的内置函数，它提供了最简单的方法来包含存在于单独文件中的模块。参考nodejs.org

只要您已在计算机中全局安装节点并在节点的上下文中执行console.log（require），将打印上述函数定义。

希望这会有所帮助。