developit / developit/microbundle
Generates Broken CommonJS From Typescript
- Langage dominant
- JavaScript
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- Forks
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Description
Microbundle creates broken CommonJS code when compiling from Typescript.
The `continue` keyword in the following code is not respected in the compiled CommonJS code.
```ts
async function brokenContinue() {
let j = 0;
while (j <= 3) {
j++;
console.log("AT THE TOP");
if (j === 1) {
console.log("\t- j === 1");
console.log("\t- waiting for 100ms");
await new Promise((resolve) => setTimeout(resolve, 100));
console.log('\t- continue, next log will be "AT THE TOP"');
continue;
}
console.log("AT THE BOTTOM");
}
}
void brokenContinue();
```
The output is:
```
$ node dist/index.cjs
AT THE TOP
- j === 1
- waiting for 100ms
- continue, next log will be "AT THE TOP"
AT THE BOTTOM <------- THIS SHOULD READ "AT THE TOP"
AT THE TOP
AT THE BOTTOM
AT THE TOP
AT THE BOTTOM
AT THE TOP
AT THE BOTTOM
```
The problem is caused by the usage of `async/await` within the while loop. Commenting out: `await new Promise((resolve) => setTimeout(resolve, 100));` produces the expected result.
**Notes:**
- Compiling using `tsc` generates JS that works correctly.
- Compiling to modern JS generates code that works correctly.
Here's a repo containing the setup that caused the issue: https://github.com/luxo-ai/breakjs
Guide de contribution
Aucun guide de contribution indexé pour ce dépôt
Piste de recherche
Start with the linked breakjs reproduction and compare dist/index.cjs with the output from tsc and modern-JavaScript compilation. Trace the async/await transformation used for the while loop; done when the generated CommonJS preserves continue behavior and prints "AT THE TOP" after the awaited promise.
Rédigé par le modèle d'indexation à partir du texte de l'issue.
Évaluation
- Stack technique
- javascript, typescript
- Domaine
- build-system, tooling
- Type d'issue
- Bug
- Difficulté
- 4/5
- Temps estimé
- 3-5 jours
- Activité
- À l'abandon
- Clarté
- Plutôt claire
- Accessibilité débutants
- 42/100