A fetch-like polyfill for userscript managers.(TM,GM,VM)
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/372917/639024/gmxhr-fetch.js
;((global, fn) => {
global.gmfetch = fn(typeof GM === 'undefined' ? {} : GM)
})(this, GM => {
if (typeof GM_xmlhttpRequest === 'undefined' && typeof GM.xmlHttpRequest === 'undefined') {
throw new Error('Either GM_xmlhttpRequest or GM.xmlHttpRequest must exists!')
}
if (typeof GM_xmlhttpRequest === 'function' && !GM.xmlHttpRequest) {
GM.xmlHttpRequest = GM_xmlhttpRequest
}
const fromEntries = e => e.reduce((acc, [k, v]) => ((acc[k] = v), acc), {})
const parseHeader = h =>
fromEntries(
h
.split('\n')
.filter(Boolean)
.map(l => l.split(':').map(tok => tok.trim()))
)
const fetch = (input, init = {}) => {
if (input instanceof Request) {
return fetch(input.url, Object.assign({}, input, init))
}
return new Promise(res => {
if (init.headers instanceof Headers) {
init.headers = fromEntries(Array.from(init.headers.entries()))
}
init.data = init.body
init = Object.assign(
{
method: 'GET',
headers: {}
},
init,
{
url: input,
responseType: 'blob'
}
)
GM.xmlHttpRequest(
Object.assign({}, init, {
onload: xhr => {
xhr.headers = parseHeader(xhr.responseHeaders)
res(new Response(xhr.response, Object.assign({}, init, xhr)))
},
onerror: xhr => {
console.log('err', xhr)
res(new Response(xhr.response, Object.assign({}, init, xhr)))
}
})
)
})
}
return fetch
})