clarify : how to pass arguments to new Headers.append .set

[tst32]

i want to construct headers for fetch (v3.1) all goes well if i pass an obj {'key':'value'} but not if i do from a variable
Example Code

import { Headers } from 'node-fetch'

const headers = new Headers()
const headers_default = [ 'referer:somesite.com', 'key1:value1' ]
headers.append(headers_defaults)

Expected behavior, if applicable
how to get headers as {'referer':'somesite.com' }?
A clear and concise description of what you expected to happen.

[jimmywarting]

The Headers constructor takes either a 2D array or an object, not a flat array...

new Headers([
  ['referer', 'somesite.com'],
  ['content-type': 'text/plain'],
  ['key1', 'value1']
])

[tst32]

Sorry, asking for one more help!
ok, there is a progress, but still not complete

const headers = new Headers()
let headers_defaults =  [
  ['User-Agent', 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:95.0) Gecko/20100101 Firefox/95.0'],
  ['referer', 'somesite.com'],
  ]
headers.append(headers_defaults)

give me

    internalBinding('errors').triggerUncaughtException(
                              ^

TypeError [ERR_INVALID_HTTP_TOKEN]: Header name must be a valid HTTP token ["[ [Array], [Array] ]"]

[jimmywarting]

headers.append(name, value) need two arguments
a name and a value, it don't accept a array

let headers_defaults =  [
  ['User-Agent', 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:95.0) Gecko/20100101 Firefox/95.0'],
  ['referer', 'somesite.com'],
]


// you can either do 
const headers = new Headers(headers_defaults)

// or 
for (let [name, value] of headers_defaults) {
  headers.append(name, value)
}

// or use spread
headers_defaults.forEach(pair => headers.append(...pair))

[tst32]

import fetch from 'node-fetch';
import { Headers } from 'node-fetch';
let headers_defaults =  [
  ['User-Agent', 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:95.0) Gecko/20100101 Firefox/95.0'],
  ['Referer', 'somesite.com'],
]
headers_defaults.forEach(pair => headers.append(...pair))

still give me

uploader-fetch/node_modules/node-fetch/src/headers.js:91
                        throw new TypeError('Failed to construct \'Headers\': The provided value is not of type \'(sequence<sequence<ByteString>> or record<ByteString, ByteString>)');
                              ^

TypeError: Failed to construct 'Headers': The provided value is not of type '(sequence<sequence> or record<ByteString, ByteString>)

UPD! :merci:

all goes well. the error above for the visibility scope problem in my func so fixed it!

When placed in inner func all rocks! 👍

export const Downloader = async (url, buffsize, headers) => {
  headers = new Headers()
  headers_defaults.forEach(pair => headers.append(...pair)) // works as expected! 
///  ... skip the rest
}