Stop nodejs child_process with browser api call - node.js

Question

I have vue (axios) making a get call to an express route which triggers a child_process of ffmpeg in an infinite loop. ffmpeg streams one file over udp , on close it re calls itself and streams another file.
I'd like to be able to kill this process from a button on a web page, but can't seem to work it out.
This is my express route code
router.get('/test', function(req, res) {
const childProcess = require('child_process');
const fs = require('fs')
const path = require('path')
//Grabs a random index between 0 and length
function randomIndex(length) {
return Math.floor(Math.random() * (length));
}
function Stream () {
const FILE_SRC = '/path/to/file'
//Read the directory and get the files
const dirs = fs.readdirSync(FILE_SRC)
.map(file => {
return path.join(FILE_SRC, file);
});
const srcs_dup = [];
const hashCheck = {}; //used to check if the file was already added to srcs_dup
var numberOfFiles = dirs.length - 1; //OR whatever # you want
console.log(numberOfFiles)
//While we haven't got the number of files we want. Loop.
while (srcs_dup.length < numberOfFiles) {
var fileIndex = randomIndex(dirs.length-1);
//Check if the file was already added to the array
if (hashCheck[fileIndex] == true) {
continue; //Already have that file. Skip it
}
//Add the file to the array and object
srcs_dup.push(dirs[fileIndex]);
hashCheck[fileIndex] = true;
}
var chosen = "'" + srcs_dup[0] + "'"
var call = "ffmpeg -re -i " + chosen + " -content_type audio/mpeg -f mp3 udp://224.1.2.3:1234"
const stop = childProcess.exec(call, { shell: true });
stop.stdout.on('data', function (data) {
console.log('stdout: ' + data.toString());
});
stop.stderr.on('data', (data) => {
console.log(`stderr: ${data}`);
});
stop.on('close', (code) => {
console.log ('child exited with code ' + code)
Stream();
});
stop.on('error', function(err) {
console.log('sh error' + err)
});
}