JavaScript tip: format console.log output

You can format the output of console.log() using CSS. Use %c in your console log string and then add an argument for the CSS.

Here’s a simple script that uses CSS formatting to make a formatted console logger:

const fl = {
  log: function (title, message, color) {
    console.log('%c%s:%c %s', 
      `color: ${color}; font-weight: bold; text-decoration: underline ${color}`,
      'color: black',
      title, message);

  info: function (message) {
    this.log('Info', message, 'green');

  warning: function (message) {
    this.log('Warning', message, 'orange');

  error: function (message) {
    this.log('Error', message, 'red');


Here is the result in the console:

console formatting

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