Prototype Pollution

function processNested(data) {
  if (!data || data.length < 1) return {}

  let d = {}, keys = Object.keys(data)

  for (let i = 0; i < keys.length; i++) {
    let key      = keys[i],
        value    = data[key],
        current  = d,
        keyParts = key
          .replace(new RegExp(/\[/g), '.')
          .replace(new RegExp(/\]/g), '')
          .split('.')

    for (let index = 0; index < keyParts.length; index++) {
      let k = keyParts[index]
      if (index >= keyParts.length - 1){
        current[k] = value
      } else {
        if (!current[k]) current[k] = !isNaN(keyParts[index + 1]) ? [] : {}
        current = current[k]
      }
    }
  }

  return d