require('mypackage.js')和require('mypackage')有什么区别? [英] What is the difference between require('mypackage.js') and require('mypackage')?

问题描述

这两个require语句的工作方式似乎相同:

Both these require statements appear to work the same way:

var Mypackage = require('mypackage.js');

var Mypackage require('mypackage');

它们之间有区别吗?

推荐答案

以下是答案:

Module.prototype.load = function(filename) {
  debug('load ' + JSON.stringify(filename) +
        ' for module ' + JSON.stringify(this.id));

  assert(!this.loaded);
  this.filename = filename;
  this.paths = Module._nodeModulePaths(path.dirname(filename));

  var extension = path.extname(filename) || '.js';
  if (!Module._extensions[extension]) extension = '.js';
  Module._extensions[extension](this, filename);
  this.loaded = true;
};

1. Node.JS 可以查看给定的模块是否为核心模块. (例如http，fs等) 在加载模块中始终优先.
2. 如果给定的模块不是核心模块(例如http，fs等)，则Node.js将开始搜索名为 node_modules 的目录.
   它将从当前目录开始(相对于 Node.JS 中当前正在执行的文件)，然后逐步向上移动文件夹层次结构，检查每个级别的node_modules文件夹. 一旦 Node.JS 找到node_modules文件夹，它将尝试将给定模块加载为(.js) JavaScript文件或命名子目录；如果找到命名的子目录，它将尝试以各种方式加载文件.因此，例如
3. 如果您请求加载模块"utils"及其目录而不是.js文件，则:
   节点.JS 将在分层目录中搜索node_modules，然后 utils通过以下方式:
   ./node_modules/utils.js
./node_modules/utils/index.js
./node_modules/utils/package.json
4. 如果 Node.JS 在上述步骤中仍然找不到文件，则Node.js将开始调查环境变量的目录路径，即在计算机上设置的 NODE_PATH (如果在Windows上，显然由Node.JS安装程序文件设置) 然后，在上述所有步骤中均未找到，则将堆栈跟踪记录打印到 stder
   例如: Error: Cannot find module 'yourfile'
   有关更多信息:链接是此处，甚至是循环的require() 解释得很好.

1. Node.JS looks to see if the given module is a core module. (e.g. http, fs, etc.) Always takes the precedence in the loading modules.
2. If the given module is not a core module (e.g. http, fs, etc.), Node.js will then begin to search for a directory named, node_modules.
   It will start in the current directory (relative to the currently-executing file in Node.JS) and then work its way up the folder hierarchy, checking each level for a node_modules folder. Once Node.JS finds the node_modules folder, it will then attempt to load the given module either as a (.js) JavaScript file or as a named sub-directory; if it finds the named sub-directory, it will then attempt to load the file in various ways. So, for example
3. If you make a request to load the module, "utils" and its a directory not a .js file then:
   Node.JS will search a hierarchical directory for node_modules and utils in the following ways:
   ./node_modules/utils.js
./node_modules/utils/index.js
./node_modules/utils/package.json
4. If Node.JS still can't find the file in above steps, Node.js will then start to look into the directory paths from environment variables i.e. NODE_PATH set on your machine(obviously set by Node.JS installer file if you are on windows) Not Found in all the above steps then, prints a stack trace to stder
   E.g.: Error:Cannot find module 'yourfile'
   For more information: link is here even the cyclic require() is explained very well.

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