polished/lib/color/hslToColorString.js.flow

A lightweight toolset for writing styles in Javascript.

// @flow
import hsl from './hsl'
import hsla from './hsla'
import PolishedError from '../internalHelpers/_errors'

import type { HslColor, HslaColor } from '../types/color'

/**
 * Converts a HslColor or HslaColor object to a color string.
 * This util is useful in case you only know on runtime which color object is
 * used. Otherwise we recommend to rely on `hsl` or `hsla`.
 *
 * @example
 * // Styles as object usage
 * const styles = {
 *   background: hslToColorString({ hue: 240, saturation: 1, lightness: 0.5 }),
 *   background: hslToColorString({ hue: 360, saturation: 0.75, lightness: 0.4, alpha: 0.72 }),
 * }
 *
 * // styled-components usage
 * const div = styled.div`
 *   background: ${hslToColorString({ hue: 240, saturation: 1, lightness: 0.5 })};
 *   background: ${hslToColorString({ hue: 360, saturation: 0.75, lightness: 0.4, alpha: 0.72 })};
 * `
 *
 * // CSS in JS Output
 * element {
 *   background: "#00f";
 *   background: "rgba(179,25,25,0.72)";
 * }
 */
export default function hslToColorString(color: HslColor | HslaColor | number): string {
  if (
    typeof color === 'object'
    && typeof color.hue === 'number'
    && typeof color.saturation === 'number'
    && typeof color.lightness === 'number'
  ) {
    if (color.alpha && typeof color.alpha === 'number') {
      return hsla({
        hue: color.hue,
        saturation: color.saturation,
        lightness: color.lightness,
        alpha: color.alpha,
      })
    }

    return hsl({
      hue: color.hue,
      saturation: color.saturation,
      lightness: color.lightness,
    })
  }

  throw new PolishedError(45)
}