Just a bunch of examples of errors that are potentially hard to find and that eslint does not break on
- Temporal dead zones
- Cyclic dependencies
Created
August 15, 2016 09:56
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ES6 pitfalls and potential danger zones with babel & webpack
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| // simple example with no issues but that generate runtime exception | |
| // solution is to redefine bar as a old fashioned function that gets hoisted | |
| 'use strict'; // added by babel | |
| foo(); | |
| // not hoisted | |
| const bar = () => 'hey from bar'; | |
| // hoisted | |
| function foo(){ | |
| console.log(bar()); // Exception | |
| } |
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| // this three file setup while having cyclic dependencies | |
| // crash at runtime with no warnings etc from webpack | |
| // a.js | |
| import {init} from './b.js' | |
| init(); | |
| // b.js | |
| import {someUtil} from './c.js' | |
| export const someConfig = 'a-really-important-string'; | |
| export const init = () => console.log('init!'); | |
| // c.js | |
| import {someConfig} from './b' | |
| let localThing = someConfig + 'random-string'; | |
| export const someUtil = (x) => x/2; | |
| // Webpack execution | |
| /** | |
| * 1. require a.js | |
| * 2. execute a.js | |
| * 3. require b.js | |
| * 4. execute b.js | |
| * 5. require c.js | |
| * 6. execute c.js | |
| * 7. require b.js and get empty exports | |
| * 8. fatal exception | |
| */ |
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