require.cache

• <Object>

当模块被加载时，它们会缓存到这个对象中。通过从该对象中删除一个键值，下次 require 时将会重新加载该模块。这不适用于 本地插件，重新加载 本地插件 会导致错误。

【Modules are cached in this object when they are required. By deleting a key value from this object, the next require will reload the module. This does not apply to native addons, for which reloading will result in an error.】

添加或替换条目也是可能的。在检查内置模块之前会先检查此缓存，如果将与内置模块同名的条目添加到缓存中，只有带有 node: 前缀的 require 调用才能接收到内置模块。请谨慎使用！

【Adding or replacing entries is also possible. This cache is checked before built-in modules and if a name matching a built-in module is added to the cache, only node:-prefixed require calls are going to receive the built-in module. Use with care!】

const assert = require('node:assert');
const realFs = require('node:fs');

const fakeFs = {};
require.cache.fs = { exports: fakeFs };

assert.strictEqual(require('node:fs'), fakeFs);
assert.strictEqual(require('node:fs'), realFs); 拷贝