Comment résoudre l'erreur "n'est pas une fonction" dans JavaScript

J'écris du JavaScript sans point-virgule.

Et j'aime vraiment ça. La langue est plus propre, à mon avis.

Vous n'aimerez peut-être pas ça, et c'est compréhensible. Mais c'est comme ça.

Les points-virgules sont facultatifs. Nous ne sommes pas obligés de les ajouter.

Parfois, cependant, nous devons faire attention. En particulier, dans Node.js, nous utilisonsrequire()pour charger des modules et des fichiers externes.

Cela peut provoquer, dans certains cas, une erreur comme celle-ci:

TypeError: require(...) is not a function

That’s a weird error, right?

Let’s look at how I got it.

I required a library, and then I had to run some code at the root level and I created an immediately-invoked async function:

const fs = require('fs')

(async () => { //… })()

JS does not see a semicolon after require(), and we start a line with a (, and JS thinks we’re trying to execute a function.

It consider require('fs') as the name of the function, which is something that could actually work if the module export returned a function.

But it’s not, so we get that ...is not a function error.

How do we fix it?

We must add a semicolon. Somewhere.

This would work:

const fs = require('fs')

;(async () => { //… })()

and also this would work:

const fs = require('fs');

(async () => { //… })()

It’s a little price we have to pay to avoid the use of semicolons everywhere.

Tip: top-level await is now a thing, you can use that instead of this structure, and it will prevent such errors.


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