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How to Alter console.log

, 31 Oct 2013 CPOL
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Adding stuff to your logs.


If you need to alter Node.JS server or JavaScript client console.log function w/o the vsprintf library, dynamically build the util.format command and execute with JavaScript eval().

Using the Code

Place the following code in your file to replace the default console.log function:

util = require('util');
console.log = function(a) {
    if (arguments.length>1) {
        var cmd = 'util.format(';
        for (i in arguments) {
            if (i>0)
                cmd += ',';
            cmd += 'arguments['+i+']';
        cmd += ')';

This is much better:

util = require('util');
console.log = function() {
    process.stdout.write((new Date()).toISOString().substring(0,19).replace('T', ' ')+': ');
    process.stdout.write(util.format.apply(this, arguments) + '\n');


  • September 15, 2013 - First version.
  • October 31, 2013 - Found a better way to do the same thing. 


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

Suggestionwhy dont use join ? Pin
h.petersen16-Sep-13 6:11
memberh.petersen16-Sep-13 6:11 
GeneralRe: why dont use join ? Pin
R%S16-Sep-13 8:48
memberR%S16-Sep-13 8:48 

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