类：vm.Module

¥Class: vm.Module

此特性仅在启用 --experimental-vm-modules 命令标志时可用。

¥This feature is only available with the --experimental-vm-modules command flag enabled.

vm.Module 类为在 VM 上下文中使用 ECMAScript 模块提供了低层接口。它是 vm.Script 类的对应物，密切反映了 ECMAScript 规范中定义的 模块记录。

¥The vm.Module class provides a low-level interface for using ECMAScript modules in VM contexts. It is the counterpart of the vm.Script class that closely mirrors Module Records as defined in the ECMAScript specification.

但是，与 vm.Script 不同，每个 vm.Module 对象都从它的创建开始绑定到上下文。与 vm.Script 对象的同步性质相比，对 vm.Module 对象的操作本质上是异步的。使用 'async' 函数可以帮助操作 vm.Module 对象。

¥Unlike vm.Script however, every vm.Module object is bound to a context from its creation. Operations on vm.Module objects are intrinsically asynchronous, in contrast with the synchronous nature of vm.Script objects. The use of 'async' functions can help with manipulating vm.Module objects.

使用 vm.Module 对象需要三个不同的步骤：创建/解析、链接和评估。以下示例说明了这三个步骤

¥Using a vm.Module object requires three distinct steps: creation/parsing, linking, and evaluation. These three steps are illustrated in the following example.

此实现位于比 ECMAScript 模块加载器 更低的级别。虽然计划提供支持，但也无法与加载器交互。

¥This implementation lies at a lower level than the ECMAScript Module loader. There is also no way to interact with the Loader yet, though support is planned.

import vm from 'node:vm';

const contextifiedObject = vm.createContext({
  secret: 42,
  print: console.log,
});

// Step 1
//
// Create a Module by constructing a new `vm.SourceTextModule` object. This
// parses the provided source text, throwing a `SyntaxError` if anything goes
// wrong. By default, a Module is created in the top context. But here, we
// specify `contextifiedObject` as the context this Module belongs to.
//
// Here, we attempt to obtain the default export from the module "foo", and
// put it into local binding "secret".

const bar = new vm.SourceTextModule(`
  import s from 'foo';
  s;
  print(s);
`, { context: contextifiedObject });

// Step 2
//
// "Link" the imported dependencies of this Module to it.
//
// The provided linking callback (the "linker") accepts two arguments: the
// parent module (`bar` in this case) and the string that is the specifier of
// the imported module. The callback is expected to return a Module that
// corresponds to the provided specifier, with certain requirements documented
// in `module.link()`.
//
// If linking has not started for the returned Module, the same linker
// callback will be called on the returned Module.
//
// Even top-level Modules without dependencies must be explicitly linked. The
// callback provided would never be called, however.
//
// The link() method returns a Promise that will be resolved when all the
// Promises returned by the linker resolve.
//
// Note: This is a contrived example in that the linker function creates a new
// "foo" module every time it is called. In a full-fledged module system, a
// cache would probably be used to avoid duplicated modules.

async function linker(specifier, referencingModule) {
  if (specifier === 'foo') {
    return new vm.SourceTextModule(`
      // The "secret" variable refers to the global variable we added to
      // "contextifiedObject" when creating the context.
      export default secret;
    `, { context: referencingModule.context });

    // Using `contextifiedObject` instead of `referencingModule.context`
    // here would work as well.
  }
  throw new Error(`Unable to resolve dependency: ${specifier}`);
}
await bar.link(linker);

// Step 3
//
// Evaluate the Module. The evaluate() method returns a promise which will
// resolve after the module has finished evaluating.

// Prints 42.
await bar.evaluate();const vm = require('node:vm');

const contextifiedObject = vm.createContext({
  secret: 42,
  print: console.log,
});

(async () => {
  // Step 1
  //
  // Create a Module by constructing a new `vm.SourceTextModule` object. This
  // parses the provided source text, throwing a `SyntaxError` if anything goes
  // wrong. By default, a Module is created in the top context. But here, we
  // specify `contextifiedObject` as the context this Module belongs to.
  //
  // Here, we attempt to obtain the default export from the module "foo", and
  // put it into local binding "secret".

  const bar = new vm.SourceTextModule(`
    import s from 'foo';
    s;
    print(s);
  `, { context: contextifiedObject });

  // Step 2
  //
  // "Link" the imported dependencies of this Module to it.
  //
  // The provided linking callback (the "linker") accepts two arguments: the
  // parent module (`bar` in this case) and the string that is the specifier of
  // the imported module. The callback is expected to return a Module that
  // corresponds to the provided specifier, with certain requirements documented
  // in `module.link()`.
  //
  // If linking has not started for the returned Module, the same linker
  // callback will be called on the returned Module.
  //
  // Even top-level Modules without dependencies must be explicitly linked. The
  // callback provided would never be called, however.
  //
  // The link() method returns a Promise that will be resolved when all the
  // Promises returned by the linker resolve.
  //
  // Note: This is a contrived example in that the linker function creates a new
  // "foo" module every time it is called. In a full-fledged module system, a
  // cache would probably be used to avoid duplicated modules.

  async function linker(specifier, referencingModule) {
    if (specifier === 'foo') {
      return new vm.SourceTextModule(`
        // The "secret" variable refers to the global variable we added to
        // "contextifiedObject" when creating the context.
        export default secret;
      `, { context: referencingModule.context });

      // Using `contextifiedObject` instead of `referencingModule.context`
      // here would work as well.
    }
    throw new Error(`Unable to resolve dependency: ${specifier}`);
  }
  await bar.link(linker);

  // Step 3
  //
  // Evaluate the Module. The evaluate() method returns a promise which will
  // resolve after the module has finished evaluating.

  // Prints 42.
  await bar.evaluate();
})();拷贝