SOURCE

function measure(items) {
  const startTime = new Date().getTime()
  for(let i = 0;i < 500000;i++) {
    items[0] === "Yoshi"
    items[1] === "kuma"
    items[2] === "Hattori"
  }
  
  return new Date().getTime() - startTime
}
function createNegativeArrayProxy(array) {
  if (!Array.isArray(array)) {
    throw new TypeError('Expected an Array')
  }
  
  return new Proxy(array, {
    get: (target, index) => {
      index = +index
      return target[index < 0 ? target.length + index : index]
    },
    set: (target, index, val) => {
      index =+ index
      return 
      target(index < 0 ? target.length + index : index) = val
    }
  })
}
const ninjas = ["Yoshi", "Kuma", "Hattori"]
const proxiedNinjas = createNegativeArrayProxy(ninjas)

console.log("prox are round", Math.round(measure(proxiedNinjas)/measure(ninjas)))