babel-plugin-import-asserts

Babel plugin that does the following:

For every import {foo, bar} from './baz'; it adds

console.assert(foo, 'foo is undefined'); 
console.assert(baz, 'baz is undefined');

below the import statement. The same goes for import foo from './baz';.

Motivation:

1. catching hard to debug errors when you 1) forget to export a thing from an index.js file and then 2) try to import this thing from that index.js file in another place

2. catch the case when you use a default import although it would have to be a regular import. (import foo from './bar' instead of import {foo} from './bar'). this happens way to often and there currently is no default safety net preventing you from doing this.

Note: Only use this for development builds, you don't wanna bloat the production bundle.

Note 2: This only works for codebases where you can guarantee that every imported thing will be instantly bound. It is theoretically possible for imported things to initially be undefined and later defined. This is because ES6 Imports are "live binding". See here for more information.

Usage

$ babel --plugins import-asserts script.js

or in a .babelrc:

{
  "stage": 0,
  "plugins": [
    "import-asserts"
  ]
}

or in webpack: loader: 'babel?{"plugins":["import-asserts"]}'}