Average 2 hex colors together in javascript

Question

Alright thought I would throw this one out there for the crowd to think over.

Given a function (written in javascript) that expects two strings

Answer 1

Very late to this party, but I was personally looking for a way to average an undefined amount of HEX values. Based on the answer @RobG, I came up with this. Granted, the more colors you add the more brown/greyish they get, but, perhaps it helps!

/**
 * Averages an array of hex colors. Returns one hex value (with leading #)
 *
 * @param {Array} colors - An array of hex strings, e.g. ["#001122", "#001133", ...]
 */
function averageHex(colors) {

  // transform all hex codes to integer arrays, e.g. [[R, G, B], [R,G,B], ...]
  let numbers = colors.map(function(hex) {
    // split in seperate R, G and B
    let split = hex.match(/[\da-z]{2}/gi);

    // transform to integer values
    return split.map(function(toInt) {
      return parseInt(toInt, 16);
    });
  });

  // reduce the array by averaging all values, resulting in an average [R, G, B]
  let averages = numbers.reduce(function(total, amount, index, array) {
    return total.map(function(subtotal, subindex) {

      // if we reached the last color, average it out and return the hex value
      if (index == array.length - 1) {

        let result = Math.round((subtotal + amount[subindex]) / array.length).toString(16);

        // add a leading 0 if it is only one character
        return result.length == 2 ? '' + result : '0' + result;

      } else {
        return subtotal + amount[subindex];
      }
    });
  });

  // return them as a single hex string
  return "#" + averages.join('');
}

console.log(averageHex(["#FF110C", "#0000AA", "#55063d", "#06551e"]));
// expected: #571b44, see also https://www.colorhexa.com/ and enter "#FF110C+#0000AA+#55063d+#06551e"