How to prevent BabelJS from making global variable of 'arguments' keyword?

Question

In a project I have this BabelJS configuration:

{
  "presets": ["es2016"]
}

And somewhere in the code there is a method using the standard JS 'arguments' keyword to deal with a dynamic range of parameters. Something like this:

const myFunction = () => {
  // pass all arguments with spread operator
  someOtherFunction(...arguments); 
}

myFunction('one', 'two', 3, {number: 4});

So far so good but when BabelJS is done, it has (1) defined 'arguments' as a global variable and (2) also in a way that is bound to fail in itself:

var arguments = arguments;

Is there a way to stop BabelJS from doing this? Either by configuration or some special comment to make exceptions?

Don't use an arrow function when you want to use the `arguments` object. — Bergi, Feb 01 '18 at 13:06

Madara's Ghost · Accepted Answer · 2018-02-01T12:27:43.880

3

Don't use the magic arguments variable.

(...args) => {
  // pass all arguments
  someOtherFunction(...args);
}

If you, for some reason, must use the arguments variable (hint, you almost always don't), you have to use .apply() like you would before ES5 was a thing.

(function() {
  someOtherFunction.apply(null, arguments);
})

edited Feb 01 '18 at 12:27

answered Feb 01 '18 at 10:15

Madara's Ghost

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Great! Thank you @Madara! – Jos Feb 01 '18 at 10:16
Yes I didn't want to use 'apply' although that is a possibility. I'm happy with your answer to avoid the issue but I still wonder why BabelJS doesn't consider 'arguments' as the keyword that it is and creates a global variable. – Jos Feb 01 '18 at 10:28
2

@Jos Arrow functions don't have arguments `var test = ()=>console.log(arguments);test()` so babel probably assumes that `arguments` is a global variable – HMR Feb 01 '18 at 10:46

How to prevent BabelJS from making global variable of 'arguments' keyword?

1 Answers1