├── README.md
├── index.js
└── package.json


/README.md:
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 1 | # babel-plugin-import-asserts
 2 | Babel plugin that does the following:
 3 | 
 4 | For every `import {foo, bar} from './baz';` it adds 
 5 | ```
 6 | console.assert(foo, 'foo is undefined'); 
 7 | console.assert(baz, 'baz is undefined');
 8 | ```
 9 | below the import statement. The same goes for `import foo from './baz';`.
10 | 
11 | Motivation: 
12 | 
13 | 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
14 | 
15 | 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. 
16 | 
17 | **Note**: Only use this for development builds, you don't wanna bloat the production bundle. 
18 | 
19 | **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](https://github.com/ModuleLoader/es6-module-loader/wiki/Circular-References-&-Bindings) for more information. 
20 | 
21 | # Usage
22 | ```
23 | $ babel --plugins import-asserts script.js
24 | ```
25 | 
26 | or in a `.babelrc`:
27 | ```
28 | {
29 |   "stage": 0,
30 |   "plugins": [
31 |     "import-asserts"
32 |   ]
33 | }
34 | ```
35 | 
36 | or in webpack:
37 | `loader: 'babel?{"plugins":["import-asserts"]}'}`
38 | 


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/index.js:
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 1 | module.exports = function (babel) {
 2 |   var t = babel.types;
 3 | 
 4 |   function console_(method, arguments) {
 5 |     return t.expressionStatement(t.callExpression(
 6 |       t.memberExpression(
 7 |         t.identifier('console'), 
 8 |         t.identifier(method)),
 9 |       arguments));
10 |   }
11 |   
12 |   function consoleTest(thing) {
13 | 
14 |     var thingIsUndefined = 
15 |       t.unaryExpression('!', t.identifier(thing));
16 | 
17 |     var consoleStatement = console_('log', 
18 |         [t.literal('['), t.identifier('__filename'), t.literal(']'), t.literal(thing + ' is undefined.')]);
19 | 
20 |     var logIfUndefined = t.logicalExpression('&&', thingIsUndefined, consoleStatement);
21 | 
22 |     return logIfUndefined;
23 | 
24 |   }
25 | 
26 | 
27 |   return new babel.Plugin("import-asserts", {
28 | 
29 |     visitor: {
30 |       ImportDeclaration: function (node, parent) {
31 |         var self = this;
32 |         node.specifiers.map(function(specifier, idx) {
33 |           var name = specifier.local.name;
34 |           self.insertAfter(consoleTest(name));
35 | 
36 |         })
37 |       }
38 |     }
39 |   });
40 | };
41 | 
42 | 


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/package.json:
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 1 | {
 2 |   "name": "babel-plugin-import-asserts",
 3 |   "version": "0.1.0",
 4 |   "description": "babel plugin that adds console.asserts which check that your imports are not undefined",
 5 |   "author": {
 6 |     "name": "Jonathan Werner"
 7 |   },
 8 |   "license": "MIT",
 9 |   "repository": {
10 |     "type": "git",
11 |     "url": "git+https://github.com/jonathanewerner/babel-plugin-import-asserts.git"
12 |   },
13 |   "peerDependencies": {
14 |     "babel-core": ">=5.2.0"
15 |   },
16 |   "main": "index.js",
17 |   "devDependencies": {
18 |     "babel": "^5.6.0"
19 |   },
20 |   "keywords": [
21 |     "babel",
22 |     "babel-plugin",
23 |     "object",
24 |     "assign",
25 |     "extend",
26 |     "polyfill"
27 |   ]
28 | }
29 | 


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