CommonJS简易版实现

Favori,Sun Aug 01 2021

Cjs Implementation

图：Mako Tsereteli

逻辑

借助nodejs的虚拟机vm模块，通过nodejs读取文件，字符串包裹文件内容一层函数，实现自定义模块参数注入

代码

需要创建3个文件来验证

index.js 入口文件
module.js 模块文件
require.js 逻辑实现文件

index.js

require('./require.js')
 
const result = myRequire('./module.js')
console.log('result',result)

module.js

myExports.default = { name: "John" };
console.log('Author',Author)

require.js

const vm = require("vm");
const path = require("path");
const fs = require("fs");
 
function myRequire(filename) {
  const pathToFile = path.resolve(__dirname, filename);
  const content = fs.readFileSync(pathToFile, "utf-8");
  const wrapper = [
    "(function(myRequire,myModule,myExports,__dirname,__filename,Author){",
    "})",
  ];
  const wrapperContent = wrapper[0] + content + wrapper[1];
  const script = new vm.Script(wrapperContent, {
    filename,
  });
  const myModule = {
    myExports: {},
  };
  const result = script.runInThisContext();
  result(
    myRequire,
    myModule,
    myModule.myExports,
    pathToFile,
    filename,
    "Favori"//自定义全局变量注入
  );
  return myModule.myExports;
}
 
global.myRequire = myRequire;

验证

在命令行工具里执行 node index.js，输出如下结果

[Running] node "./index.js"
Author Favori
result { default: { name: 'John' } }
 
[Done] exited with code=0 in 0.051 seconds

到此我们就用最简易的方式实现了一个自定义模块加载器，觉得不错的收藏一下吧！