Foo

foo.js

const https = require("https");
const querystring = require("querystring");
const fs = require("fs");
const path = require("path");

(async () => {
	// Root of json file should be an array..
	// []
	const LOG_FILE_PATH = path.resolve(__dirname, "./log.json");

	const endpoint = "http://localhost:3000/post";
	const num = "foo-num";
	const TOKEN = "foo-token";
	const APP_ID = "foo-app-id";
	const sessionID = "foo-sessionID";

	const requestBody = {
		rcx_session: sessionID,
		command: JSON.stringify({
			call: {
				numbers: num,
				type: 1,
			},
		}),
	};

	const httpsAgent = new https.Agent({
		rejectUnauthorized: true,
	});

	const finalBody = querystring.stringify({
		token: TOKEN,
		app: APP_ID,
		...requestBody,
	});

	const result = await fetch(endpoint, {
		method: "POST",
		headers: { "Content-Type": "application/x-www-form-urlencoded" },
		body: finalBody,
		agent: httpsAgent,
	});

	/**
	 * LOGGING
	 *
	 * Idk what all you want to log....
	 */

  //
  // Collect data to log (you may need to change some of this....)
  //

  // Data we will log to LOG_FILE_PATH
	const dataToLog = {
		logTimeUTC: new Date().toUTCString(),
		request: {
			method: "POST",
			headers: { "Content-Type": "application/x-www-form-urlencoded" },
			token: TOKEN,
			app: APP_ID,
			requestBody,
			agent: httpsAgent,
		},
		response: {
      status: result.status,
      headers: {},
      body: "",
      url: result.url,
      type: result.type,
    }
	};

  // Get headers to log (idk)
  for (const [key, val] of result.headers.entries()) {
    dataToLog.response.headers[key] = val;
  }
  // Get body to log (idk)
  dataToLog.response.body = await result.text(); // <-- like idk what your response looks like....

  //
  // Misc logging/file related funcs.
  //

  // Create a file if it doesn't exist.
	async function createLogFileIfNotExists(path) {
		const logFileExists = await fs.existsSync(path);
		if (!logFileExists) {
			await fs.writeFileSync(path, JSON.stringify([]));
		}
	}

  // Get existing file data.
	async function getExistingLogDataAsJSON(path) {
		let existingLogs = await fs.readFileSync(path, "utf-8");
		if (!existingLogs) {
			// File exists just no data
			existingLogs = "[]"; // make it a string so when we call JSON.parse below it ddoesn't error.
		}
		return JSON.parse(existingLogs);
	}

  // Update file data and write to disk.
	async function addDataToLogsAndWriteToDisk(path, existingLogs, dataToLog) {
		existingLogs.push(dataToLog);
		const jsonString = JSON.stringify(existingLogs, null, 2); // `null, 2` params aren't needed, they just format the file so it's easier to read.
		await fs.writeFileSync(path, jsonString);
	}

  //
  //
  // Actually read/write to log file..
  //
  //
	try {
		await createLogFileIfNotExists(LOG_FILE_PATH);
		const logs = await getExistingLogDataAsJSON(LOG_FILE_PATH);
		await addDataToLogsAndWriteToDisk(LOG_FILE_PATH, logs, dataToLog);
	} catch (err) {
		console.log("Error reading/writing log file!", { error: err, request: dataToLog });
	}
})();