Parsing XML in background script with import or DOMParser

[MinaroShikuchi]

I have a chrome.alarm that fetch every 1 hour an URL.
The returned content is RSS as xml.
I would like to parse it with an external package or with the DOMParser.

I'm using vite and svelte in the vite.config.ts

import { build, defineConfig } from 'vite'
import { svelte } from '@sveltejs/vite-plugin-svelte'
import { crx } from "@crxjs/vite-plugin";
import manifest from './manifest.json' assert { type: 'json' } 

export default defineConfig({
  plugins: [svelte(), crx({ manifest })],
});

With an external package I get

import { parseStringPromise } from "xml2js";

await fetch(url, {
    headers: {
      Accept: "application/xml",
    },
  })
    .then(async (response) => {
      const data = await response.text();
      return await parseStringPromise(data);
    })
    .catch((error) => console.error(error))

Uncaught TypeError: Cannot read properties of undefined (reading 'prototype')

And with DOMParser since DOM is not available in background script

export default function parseXmlToJson(xml: string) {
 return new DOMParser().parseFromString(xml, "text/xml");
}

await fetch(url, {
    headers: {
      Accept: "application/xml",
    },
  })
    .then(async (response) => {
      const data = await response.text();
      return parseXmlToJson(data);
    })
    .catch((error) => console.error(error))

Error handling response: ReferenceError: DOMParser is not defined

Do you have any idea how to achieve this ?

[jacksteamdev]

This is a current limitation of MV3, but the new Offscreen API should allow you to do this. I believe it's in canary right now.

I'd probably try using an NPM library that works with service workers.

[MinaroShikuchi]

I solved it with some custom regex but it's not ideal