Fun experiment based on idea from https://www.twitch.tv/lunatic_mag

2048-Vector-Movement.js

function vectorMove(vector) {
  for (let i = vector.length - 2; i >= 0; i--) {
    if (vector[i] === 0) continue
    for (let j = i + 1; j < vector.length; j++) {
      if (vector[i] !== vector[j] && vector[j] !== 0) break
      if (vector[j] === 0) {
        vector[j] = vector[i]
      } else {
        vector[j] *= 2
      }
      vector[i] = 0
      i = j
    }
  }
}
function testVector(vector) {
  console.log('Before:', vector)
  vectorMove(vector)
  console.log('After:', vector)
}
testVector([2,2,4,4])
testVector([2,2,4,2])