Organizing array of [r, g, b, a, r, g, b, a] to an object array [{r, g, b, a}, {r, g, b, a}]

pixel-reduce.js

const pixels = ['r','g','b','a','r','g','b','a','r','g','b','a'];

const propMap = ['r', 'g', 'b', 'a'];

const rgbas = pixels.reduce((acc, curr, i) => {
  const mod = i%4;
  switch (mod) {
    case 0:
      return [...acc, {r: curr}];
    default:
      const index = Math.floor(i/4);
      const color = acc[index];
      color[propMap[mod]] =  curr;
      return acc;
  }
}, []);

console.log(rgbas);