How do I HTTP GET a .js file and extract 'exports' variables?

I am writing a site in Laravel to complement a game written in Node. It pulls information directly from the game's .js files stored on GitHub and the plan is to use Vue to generate some nice HTML to display the data.

The .js files are of the form:

'use strict'

let x = {...};

exports.x = x;

I can import the files using a PHP request (simply using 'file') and pass them to JS with either jQuery.getScript or axios.get (so far). However, I am having real trouble coming up with a way to extract the 'x' values here under exports. If I were writing a JS app in node, I would simply do the following:

var xFile = require('xFile');

var x = xFile.x;

However, I can't figure out how to do that here as both GET methods return a string, not a JS file. JSON.parse() doesn't work, and I would like to come up with a solution that doesn't just replace the non-JSON text as I would need a reusable solution for other files. I don't suppose anybody has any ideas?

Thanks so much!