btt_stock_tracker_node.js

/**
 *  This script uses a stock market API
 *  to display real-time stock market info
 *  on the Touch Bar using BetterTouchTool.
 *
 *  Note:
 *      Axios must be installed wherever
 *      this JavaScript file is located.
 *      (i.e. `npm install axios`)
 */

// Import axios (handles API requests)
const axios = require('axios');

// Configuration
const params = {
    symbol: 'AAPL',      // Select the stock you want to track
    token: ''           // Get an API token from https://finnhub.io/register
};

// Form a request URL with search params
const APIEndpoint = new URL('https://finnhub.io/api/v1/quote');
for (const key in params)
    APIEndpoint.searchParams.append(key, params[key]);
const requestURL = APIEndpoint.href;

// Axios: execute GET request
axios.get(requestURL).then(result => {
    const data = result.data;

    // Extract properties from API request result (Object)
    let current = data.c,       // current price
        high = data.h,          // high
        low = data.l,           // low
        open = data.o,          // open
        prevClose = data.pc,    // previous close
        time = data.t;          // timestamp

    // Calculate new values
    let todayPercentChange = current - open / open * 100;

    // Format values for ouput (use 2 decimal places)
    const decimalPlaces = 2;
    current = parseFloat(current).toFixed(decimalPlaces);
    todayPercentChange = parseFloat(todayPercentChange).toFixed(decimalPlaces);

    // Insert conditoinal symbols for clarity
    let positiveSymbol = '';
    if (todayPercentChange > 0) positiveSymbol = '+';

    // Display formatted stock info on touch bar
    const returnToBTT = `${params.symbol}: $${current} (${positiveSymbol}${todayPercentChange}\%)`;
    console.log(returnToBTT);   // AAPL: $273.60 (+173.60%)
});