Processing a POST or GET request without a server

To achieve the requirement you can use Chromium or Chrome browser launched with --allow-file-access-from-files flag set.

fetch() does not permit requesting local files having file: protocol, though XMLHttpRequest() does. fetch() does allow requesting data URL and Blob URL.

For

some javascript file , which takes these parameter "name " and returns it in uppercase , like "VIM "

Worker can be used to get the contents of a local file, manipulate the content, then postMessage() can be called to communicate with main thread.

For example

worker.js

onmessage = e => { // do stuff let url = new URL(e.data); let [[,param]] = [...url.searchParams]; // get query string parameter `'vim'` let request = new XMLHttpRequest(); request.open('GET', 'file:///path/to/local/file' /* e.data */); request.onload = e => { console.log(request.responseText); // `setTimeout()` can be inside `load` handler } request.send(); // asynchronous response setTimeout(() => { // set `data URL` that `fetch()` will request postMessage(`data:text/plain,${param.toUpperCase()}`); }, Math.floor(Math.random() * 2000)); } 

At console or within a script

const localRequest = async(url) => { const request = await fetch(await new Promise(resolve => { const worker = new Worker('worker.js'); worker.onmessage = e => { resolve(e.data); worker.terminate(); } worker.postMessage(url); })); const response = await request.text(); console.log(response); } localRequest('file:///verse.txt?name=vim');