/** * Get luminance from a HEX color. * * @since Twenty Twenty-One 1.0 * * @param {string} hex - The hex color. * * @return {number} - Returns the luminance, number between 0 and 255. */ function twentytwentyoneGetHexLum( hex ) { // jshint ignore:line var rgb = twentytwentyoneGetRgbFromHex( hex ); return Math.round( ( 0.2126 * rgb.r ) + ( 0.7152 * rgb.g ) + ( 0.0722 * rgb.b ) ); } /** * Get RGB from HEX. * * @since Twenty Twenty-One 1.0 * * @param {string} hex - The hex color. * * @return {Object} - Returns an object {r, g, b} */ function twentytwentyoneGetRgbFromHex( hex ) { var shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i, result; // Expand shorthand form (e.g. "03F") to full form (e.g. "0033FF"). hex = hex.replace( shorthandRegex, function( m, r, g, b ) { return r.toString() + r.toString() + g.toString() + g.toString() + b.toString() + b.toString(); } ); result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec( hex ); return result ? { r: parseInt( result[1], 16 ), g: parseInt( result[2], 16 ), b: parseInt( result[3], 16 ) } : null; }