react-conventions/src/components/internal/ColorLuminance.js

An open source set of React components that implement Ambassador's Design and UX patterns.

const ColorLuminance = (hex, lum) => {
  if (typeof hex === 'undefined' || !hex) {
    return false
  }

  // Validate hex string
  hex = String(hex).replace(/[^0-9a-f]/gi, '')
  if (hex.length < 3) {
    return false
  }
  if (hex.length < 6) {
    hex = hex[0]+hex[0]+hex[1]+hex[1]+hex[2]+hex[2]
  }
  lum = lum || 0

  let rgb = "#", c, i

  for (i = 0; i < 3; i++) {
    c = parseInt(hex.substr(i*2,2), 16)
    c = Math.round(Math.min(Math.max(0, c + (c * lum)), 255)).toString(16)
    rgb += ("00"+c).substr(c.length)
  }

  return rgb
}

export default ColorLuminance