Chuck this is how I run filter scripts. I probably will convert to requireFromString.

runfilterscript.js

function runFilterScript (host, callback) { //3/23/20 by DW
	var f = getFullFilePath (domainsPath) + host + filterFname;
	fs.readFile (f, function (err, data) {
		if (err) {
			callback (false); //file doesn't exist -- we didn't run the filter script
			}
		else {
			try {
				const options = {
					httpRequest,
					serveLocalFile: function (f) {
						console.log ("serveLocalFile (" + f + ")");
						serveFile (f, config);
						}
					};
				const filterfile = __dirname + "/" + f;
				if (require.cache [filterfile] !== undefined) {
					delete require.cache [filterfile];
					}
				require (filterfile).filter (options, function (err, httpResponse) {
					if (err) {
						httpRespond (500, "text/plain", err.message);
						callback (true); //we handled it
						}
					else {
						if (httpResponse.flNotHandled) { //the plugin doesn't want this, let other functions in pagePark have a try
							callback (false);
							}
						else {
							httpRespond (httpResponse.code, httpResponse.type, httpResponse.val);
							callback (true); //we handled it
							}
						}
					});
				}
			catch (err) {
				httpRespond (500, "text/plain", err.message);
				callback (true); //we handled it
				}
			}
		});
	}