isArrayLike

检测是否为数组或者伪数组

const isArrayLike = function isArrayLike(obj) {
  let length = !!obj && "length" in obj && obj.length,
    type = toType(obj)
  if (isFunction(obj) || isWindow(obj)) return false
  return type === "array" || length === 0 ||
    typeof length === "number" && length > 0 && (length - 1) in obj
}

注意：这里用到toType&isFunction&isWindow方法