node.js require() cache - possible to invalidate?

Question

From the node.js documentation:

Modules are cached after the first time they are loaded. This means (among other things) that every call to require(\'

Answer 1

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.

Suppose you have:

script a.js:

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

and script b.js:

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

when you do:

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

you will get:

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

now if you edit your b.js:

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

and do:

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

you will get:

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

===

The above is valid if directly running node.js. However, if using tools that have their own module caching system, such as jest, the correct statement would be:

jest.resetModules();