类:vm.Module
添加于:v13.0.0、v12.16.0
Stability: 1 - 实验性
此函数仅在启用--experimental-vm-modules
命令标志时可用。
vm.Module
类为在 VM 上下文中使用 ECMAScript 模块提供了一个低级接口。它是 vm.Script
类的对应物,与 ECMAScript 规范中定义的 Module Record 非常相似。
然而,与 vm.Script
不同的是,每个 vm.Module
对象从创建时就绑定到上下文。 vm.Module
对象上的操作本质上是异步的,与 vm.Script
对象的同步性质相反。使用'async' 函数可以帮助操作vm.Module
对象。
使用vm.Module
对象需要三个不同的步骤:创建/解析、链接和评估。这三个步骤在以下示例中进行了说明。
此实现位于比 ECMAScript Module loader 更低的级别。尽管计划提供支持,但目前还无法与 Loader 交互。
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(); })();
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注:本文由纯净天空筛选整理自nodejs.org大神的英文原创作品 vm.Module。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。