Adding axios headers

[Keimeno]

Issue

There are no suggestions in TypeScript for HTTP Headers.

Solved

Added separate headers.ts file in root and imported the AxiosHeaders type into the declaration file.
Removed all Headers prefixed with X- from autosuggestions, as it is deprecated according to RFC 6648.

[pelepelin]

What's the meaning of object & ?

[Keimeno]

Usually you assign a value to a key in an object like this:

const obj = {
    key: value
}

But if we work with headers, we want a String as key as well. Like this:

const obj = {
    'key': value
}

This however gives us an error in typescript. So we need to create a custom type, the LooseObject. But it has to inherit everything from a normal object, that is why you see the object &.

With this we can use strings as keys for objects:

const obj: LooseObject = {
    'key': value
}

And the AxiosHeaders type implements the LooseObject

[pelepelin]

Sorry, I didn't get it. This does not give me any error:

type LooseObject = {
    [key: string]: string;
};

type AxiosHeaders = LooseObject & {
    'Accept'?: string;
};

const y: AxiosHeaders = {
    Accept: 'x-any',
    'x-forwarded-for': '8.8.8.8',
    anything: 'other'
};

What's the case where the result with object & would be different?

[Keimeno]

Yea you're correct, my mistake. Fixed it now.

[pelepelin]

Probably, restricting header values to strings is a good thing, however, it's a compatibility break, as currently numbers and booleans can be passed and are properly handled.

[chinesedfan]

Closed in favor of #3237 (comment). Thanks for your contribution all the same.

[pelepelin]

While argument in the comment does apply, headers should be key:any, not plain any.