Adding timestamps to all console messages

Question

I have a complete, deployed, Express-based project, with many console.log() and console.error() statements throughout. The project runs using forever, directing the st

Answer 1

If you wish, you may create a custom logger for your application by extending the Node's build in "Console" class. Kindly refer to the following implementation

"use strict";

const moment = require('moment');
const util = require('util');
const Console = require('console').Console;

class Logger extends Console {
    constructor(stdout, stderr, ...otherArgs) {
        super(stdout, stderr, ...otherArgs);
    }

    log(...args) {
        super.log(moment().format('D MMM HH:mm:ss'), '-', util.format(...args));
    }

    error(...args) {
        super.error(moment().format('D MMM HH:mm:ss'), '-', util.format(...args));
    }
}

module.exports = (function() {
    return new Logger(process.stdout, process.stderr); 
}());

After that, you may use it in your code as :

const logger = require('./logger');

logger.log('hello world', 123456);
logger.error('some error occurred', err);

Answer 2

Use event listener like this,

process.on('error', function() { 
   console.log('Error Occurred.');

   var d = Date(Date.now()).toString();
   console.log.call(console, d); // Wed Aug 07 2019 23:40:07 GMT+0100 (GMT+01:00)
});

happy coding :)

Answer 3

If you want a solution without another external dependency but you want to keep the full functionalities of console.log (multiple parameters, variable insertion) you can use the following code:

var log = console.log;

console.log = function () {
    var first_parameter = arguments[0];
    var other_parameters = Array.prototype.slice.call(arguments, 1);

    function formatConsoleDate (date) {
        var hour = date.getHours();
        var minutes = date.getMinutes();
        var seconds = date.getSeconds();
        var milliseconds = date.getMilliseconds();

        return '[' +
               ((hour < 10) ? '0' + hour: hour) +
               ':' +
               ((minutes < 10) ? '0' + minutes: minutes) +
               ':' +
               ((seconds < 10) ? '0' + seconds: seconds) +
               '.' +
               ('00' + milliseconds).slice(-3) +
               '] ';
    }

    log.apply(console, [formatConsoleDate(new Date()) + first_parameter].concat(other_parameters));
};

You can modify the formatConsoleDate function to format the date how you want.

This code needs to be written only once on top of your main JavaScript file.

console.log("he%s", "y") will print something like this:

[12:22:55.053] hey

Answer 4

This isn't a direct answer, but have you looked into winston.js? It has a ton more logging options including logging to a json file or database. These always have timestamps by default. Just a thought.

Answer 5

Create a file with the following:

var log = console.log;

console.log = function(){
  log.apply(console, [Date.now()].concat(arguments));
};

Require it in your app before you log anything. Do the same for console.error if needed.

Note that this solution will destroy variable insertion (console.log("he%s", "y") // "hey") if you're using that. If you need that, just log the timestamp first:

log.call(console, Date.now());
log.apply(console, arguments);

Answer 6

You could also use the log-timestamp package. It's quite straightforward, and customizable as well.