Generates a MongoDB-style ObjectId in Node.js

mongodb-objectid.js

/**
 * Generates a MongoDB-style ObjectId in Node.js. Uses nanosecond timestamp in place of counter; 
 * should be impossible for same process to generate multiple objectId in same nanosecond? (clock 
 * drift can result in an *extremely* remote possibility of id conflicts).
 *
 * @returns {string} Id in same format as MongoDB ObjectId.
 */
function objectId() {
    const os = require('os');
    const crypto = require('crypto');

    const seconds = Math.floor(new Date()/1000).toString(16);
    const machineId = crypto.createHash('md5').update(os.hostname()).digest('hex').slice(0, 6);
    const processId = process.pid.toString(16).slice(0, 4).padStart(4, '0');
    const counter = process.hrtime()[1].toString(16).slice(0, 6).padStart(6, '0');

    return seconds + machineId + processId + counter;
}