node.js require()缓存-可能无效? [英] node.js require() cache - possible to invalidate?

问题描述

从node.js文档中:

From the node.js documentation:

模块在第一次加载后被缓存.这意味着(除其他事项外)每次对require('foo')的调用都将获得完全相同的返回对象，如果它可以解析为相同的文件.

Modules are cached after the first time they are loaded. This means (among other things) that every call to require('foo') will get exactly the same object returned, if it would resolve to the same file.

是否有一种方法可以使此缓存无效?也就是说，对于单元测试，我希望每个测试都可以在一个新对象上进行.

Is there a way to invalidate this cache? i.e. for unit testing, I'd like each test to be working on a fresh object.

推荐答案

即使存在循环依赖关系，也始终可以安全地删除require.cache中的条目.因为在删除时，您只删除对缓存的模块对象的引用，而不是对模块对象本身的引用，所以不会对GC对象进行GC，因为在循环依赖的情况下，仍然有一个对象引用此模块对象.

You can always safely delete an entry in require.cache without a problem, even when there are circular dependencies. Because when you delete, you just delete a reference to the cached module object, not the module object itself, the module object will not be GCed because in case of circular dependencies, there is still a object referencing this module object.

假设您有

脚本a.js:

var b=require('./b.js').b;
exports.a='a from a.js';
exports.b=b;

和脚本b.js:

var a=require('./a.js').a;
exports.b='b from b.js';
exports.a=a;

当您这样做:

var a=require('./a.js')
var b=require('./b.js')

您将得到:

> a
{ a: 'a from a.js', b: 'b from b.js' }
> b
{ b: 'b from b.js', a: undefined }

现在是否编辑b.js:

now if you edit your b.js:

var a=require('./a.js').a;
exports.b='b from b.js. changed value';
exports.a=a;

然后做:

delete require.cache[require.resolve('./b.js')]
b=require('./b.js')

您将得到:

> a
{ a: 'a from a.js', b: 'b from b.js' }
> b
{ b: 'b from b.js. changed value',
  a: 'a from a.js' }

这篇关于node.js require()缓存-可能无效?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！