Exposing the Axios constructor in index.d.ts

[TimWolla]

This patch allows TypeScript users to extend the Axios class without
the type checker complaining.

see 7548f2f

---

Fixes #3017

[TimWolla]

Could you please take a look? After I used the “Update branch” button on April, 8th Travis is green instead of a stuck yellow as well.

[donaldpipowitch]

@chinesedfan Is there something which still needs to be done for this MR?

[ArrayKnight]

Would it be possible to get this merged soon, please?

[jasonsaayman]

Will look at this as soon as I can

[TimWolla]

@remcohaszing Can you return the favor and review this one, please? The reason behind this change is being able to class Foo extends Axios with import { default as axios, Axios } from 'axios';.

It should be non-breaking, but a second pair of eyes would be helpful.

[remcohaszing]

I looked into it. This allow to use the following statements that were previously not possible:

import axios from 'Axios';

const foo = new axios.Axios();  // Use Axios constructor
foo instanceof axios.Axios;  // Instanceof check for Axios instance
foo('/');  // This is unsupported, and now also an error in TypeScript

The instanceof check doesn’t work for instances created axios.create(), but the call expression does work in that case.

All of these cases are properly handled by the new type definitions, and it’s non-breaking. LGTM 😃

[TimWolla]

@jasonsaayman I'd appreciate if you could take a look at this one. I'm happy to answer all your questions about it, like we did in #2797 👍

[TimWolla]

@jasonsaayman Friendly ping. I just rebased this PR once again and it's already been reviewed by Remco.

[TimWolla]

@jasonsaayman Any chance? I just rebased the PR onto the latest master to allow for the GitHub Actions to run. You'll need to approve them once, though, because technically I'm a new contributor.

[jasonsaayman]

@TimWolla thanks for being so tenacious, I am merging this now 🥳

[TimWolla]

Thanks! 🚀