A console.log with a little more... flair.

rainbowLog.ts

const rainbow = (s: string) => {
  const colors = [
    'red',
    'orange',
    'yellow',
    'green',
    'blue',
    'indigo',
    'violet',
  ]
  const logArray: string[] = []
  let colorCounter = 0
  let colorDirection = 1
  let logString = ''

  s.split('').forEach((c) => {
    const color = colors[colorCounter]
    let formattedString = c
    if (!c.match(/\s/)) {
      colorDirection = (colorCounter >= (colors.length - 1))
        ? -1
        : (colorCounter <= 0)
          ? 1
          : colorDirection
      colorCounter += colorDirection
      formattedString = `%c${c}`
      logArray.push(`color:${color};`)
    }
    logString += formattedString
  })

  return [logString, ...logArray]
}

interface Console {
  rainbow: (s: string) => void
}

console.rainbow = (s: string) => console.log(...rainbow(s))