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From my understanding, webpack (and other similar bundlers) ensures that if the same module is required across multiple parts of the app:

  • That code will only be loaded once
  • Each time the same module is required, a new instance is created, rather than all sharing the same scope

Firstly, are my above assumptions correct? If so, is it bad optimisation to have multiple instances of the same module being created?

In my example I am creating an app that will be using ThreeJS. This is a rather large library. Many of the modules in my app will want to require this library.

Is it bad practice to keep on requiring a library like this? Or should I be passing a single instance from module to module instead of requiring multiple times?

I'd be interested to know if there are any common patterns for dealing with this, if it is indeed an issue.

AlexKempton
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1 Answers1

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This assumption:

Each time the same module is required, a new instance is created, rather than all sharing the same scope

is wrong for two reasons:

  • Whether an instance is created or not, will depend on what is returned by the required module (it could return nothing).
  • Even if the module initialises an instance, only one will be created, as the code in the module is only run once.

With that said, requiring the same module multiple times should have no impact in performance.

Hugo Silva
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