headers-polyfill
v4.0.3
Published
A native "Headers" class polyfill.
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Readme
headers-polyfill
A Headers
class polyfill and transformation library.
Motivation
Various request issuing libraries utilize a different format of headers. This library chooses the Headers
instance as the middle-ground between server and client, and provides functions to convert that instance to primitives and vice-versa.
Install
npm install headers-polyfill
Polyfill
This package exports the Headers
class that polyfills the native window.Headers
implementation. This allows you to construct and manage headers using the same API in non-browser environments.
import { Headers } from 'headers-polyfill'
const headers = new Headers({
Accept: '*/*',
'Content-Type': 'application/json',
})
headers.get('accept') // "*/*"
Methods
The Headers
polyfill instance supports the same methods as the standard Headers
instance:
As well as the iterator methods:
Transformations
getRawHeaders()
Returns an object consisting of the header name/value pairs but preserving raw header names.
const headers = new Headers({
Accept: '*/*',
'Content-Type': 'application/json',
})
headers.raw()
// { "Accept": "*/*", "Content-Type": "application/json" }
Headers ⭢ N
headersToString: (h: Headers): string
import { headersToString } from 'headers-polyfill'
headersToString(
new Headers({
connection: 'keep-alive',
'content-type': ['text/plain', 'image/png'],
})
)
// connetion: keep-alive
// content-type: text/plain, image/png
headersToList: (h: Headers): Array<[string, string | string[]]>
import { headersToList } from 'headers-polyfill'
headersToList(
new Headers({
connection: 'keep-alive',
'content-type': ['text/plain', 'image/png'],
})
)
// [['connection', 'keep-alive'], ['content-type', ['text/plain', 'image/png']]]
headersToObject: (h: Headers): Record<string, string | string[]>
import { headersToObject } from 'headers-polyfill'
headersToObject(
new Headers({
connection: 'keep-alive',
'content-type': ['text/plain', 'image/png'],
})
)
// { connection: 'keep-alive', 'content-type': ['text/plain', 'image/png'] }
N ⭢ Headers
stringToHeaders: (s: string): Headers
import { stringToHeaders } from 'headers-polyfill'
const stringToHeaders(`
connection: keep-alive
content-type: text/plain, image/png
`)
// Headers { connection: 'keep-alive', 'content-type': ['text/plain', 'image/png'] }
listToHeaders: (l: Array<[string, string | string[]]>): Headers
import { listToHeaders } from 'headers-polyfill'
listToHeaders([
['connection', 'keep-alive'],
['content-type', ['text/plain', 'image/png']],
])
// Headers { connection: 'keep-alive', 'content-type': ['text/plain', 'image/png'] }
objectToHeaders: (o: Record<string, string | string[] | undefined>): Headers
import { objectToHeaders } from 'headers-polyfill'
objectToHeaders({
connection: 'keep-alive',
'content-type': ['text/plain', 'image/png'],
})
// Headers { connection: 'keep-alive', 'content-type': ['text/plain', 'image/png'] }
Utilities
reduceHeadersObject: <R>(o: Record<string, string | string[]>, reducer: (acc: R, name: string, value: string | string[]) => R) => R
import { reduceHeadersObject } from 'headers-polyfill'
reduceHeadersObject <
HeadersObject >
({
Accept: '*/*',
'Content-Type': ['application/json', 'text/plain'],
},
(headers, name, value) => {
headers[name.toLowerCase()] = value
return headers
},
{})
// { 'accept': '*/*', 'content-type': ['application/json', 'text/plain'] }
appendHeader: (o: Record<string, string | string[]>, n: string, v: string | string[]): Record<string, string | string[]>
import { appendHeader } from 'headers-polyfill'
appendHeader(
{ 'content-type': 'application/json' },
'content-type',
'text/plain'
)
// { 'content-type': ['application/json', 'text/plain']}
flattenHeadersList: (l: Array<[string, string | string[]]>): Array<string, string>
import { flattenHeadersList } from 'headers-polyfill'
flattenHeadersList([['content-type', ['text/plain', 'image/png']]])
// ['content-type', 'text/plain, image/png']
flattenHeadersObject: (o: Record<string, string | string[]>): Record<string, string>
import { flattenHeadersObject } from 'headers-polyfill'
flattenHeadersObject({
'content-type': ['text/plain', 'image/png'],
})
// { 'content-type': 'text/plain, image/png' }