Colors in JavaScript console

Question

Can Chrome\'s built-in JavaScript console display colors?

I want errors in red, warnings in orange and console.log\'s in green. Is that possible?

Answer 1

I recently wanted to solve for a similar issue and constructed a small function to color only keywords i cared about which were easily identifiable by surrounding curly braces {keyword}.

This worked like a charm:

var text = 'some text with some {special} formatting on this {keyword} and this {keyword}'
var splitText = text.split(' ');
var cssRules = [];
var styledText = '';
_.each(splitText, (split) => {
    if (/^\{/.test(split)) {
        cssRules.push('color:blue');
    } else {
        cssRules.push('color:inherit')
    }
    styledText += `%c${split} `
});
console.log(styledText , ...cssRules)

technically you could swap out the if statement with a switch/case statement to allow multiple stylings for different reasons

Answer 2

I wrote a npm module that gives one the possibility to pass:

• Custom colors - to both text and background;
• Prefixes - to help identify the source, like [MyFunction]
• Types - like warning, success, info and other predefined message types

https://www.npmjs.com/package/console-log-plus

Output (with custom prefixes):

clp({
  type: 'ok',
  prefix: 'Okay',
  message: 'you bet'
});
clp({
  type: 'error',
  prefix: 'Ouch',
  message: 'you bet'
});
clp({
  type: 'warning',
  prefix: 'I told you',
  message: 'you bet'
});
clp({
  type: 'attention',
  prefix: 'Watch it!',
  message: 'you bet'
});
clp({
  type: 'success',
  prefix: 'Awesome!',
  message: 'you bet'
});
clp({
  type: 'info',
  prefix: 'FYI',
  message: 'you bet'
});
clp({
  type: 'default',
  prefix: 'No fun',
  message: 'you bet'
});

Output (without custom prefixes):

Input:

clp({
  type: 'ok',
  message: 'you bet'
});
clp({
  type: 'error',
  message: 'you bet'
});
clp({
  type: 'warning',
  message: 'you bet'
});
clp({
  type: 'attention',
  message: 'you bet'
});
clp({
  type: 'success',
  message: 'you bet'
});
clp({
  type: 'info',
  message: 'you bet'
});
clp({
  type: 'default',
  message: 'you bet'
});

To make sure the user won't render an invalid color, I wrote a color validator as well. It will validate colors by name, hex, rgb, rgba, hsl or hsla values

Answer 3

There are a series of inbuilt functions for coloring the console log:

//For pink background and red text
console.error("Hello World");  

//For yellow background and brown text
console.warn("Hello World");  

//For just a INFO symbol at the beginning of the text
console.info("Hello World");  

//for custom colored text
console.log('%cHello World','color:blue');
//here blue could be replaced by any color code

//for custom colored text with custom background text
console.log('%cHello World','background:red;color:#fff')