optional dependencies when using es6 import/export

3 thoughts on “optional dependencies when using es6 import/export”

1. try {
     require("external");
   } catch(e) {
     // fallback
   }

2. Thanks

   But 😄
   to keep an es6 (or esm) project consistent, I don’t want to use require when importing anything. I use the import keyword.
   As a fallback, we are also offering a UMD module, built with webpack. The UMD definition has the option to automatically define the require as optional, but, as i wrote, it is not a flag anywhere I can find.
   You can see it here – https://github.com/webpack/webpack/blob/master/lib/UmdMainTemplatePlugin.js#L162
   and here for AMD externals as global – https://github.com/webpack/webpack/blob/master/lib/UmdMainTemplatePlugin.js#L97

   All I actually want to know is how to get the (external) module to be defined as optional, without using the try-catch method.

3. Hi everyone 👋

   I’ve read a few issues across GitHub of libraries using optional externals via a try/catch. None of them are fully resolved.

   The major issue is that you get a warning Module not found: Error: Can't resolve 'xxx'.

   If a library wants to offer optional adapters for third-party dependencies out-of-the-box, its users will receive a warning for each optional dependencies that this user doesn’t need. I’m not sure that this is an acceptable behaviour.

   To be more precise.

   Current context: wrap require('xxx') in a try/catch and register xxx as an external in webpack configurations.
   Current behaviour: library users get WARNING Module not found: Error: Can't resolve 'xxx'
   Expected behaviour: no warning

   Am I missing something?

   Here’s a couple of those issues I was talking about:

   • wowserhq/blizzardry#101
   • lorisleiva/javel#3 (comment)

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