js: 实现一个cached缓存函数计算结果

function cached(func) {
  // 缓存计算结果
  const cache = Object.create(null)
  // 返回一个缓存函数
  return function (...args) {
    let cache_key = JSON.stringify(args)
    let result = null
    if (cache_key in cache) {
      result = cache[cache_key]
    } else {
      result = func.apply(this, args)
      cache[cache_key] = result
    }
    return result
  }
}

function computed(a, b) {
  console.log('computed')
  return a + b
}
let cachedComputed = cached(computed)
console.log(cachedComputed(2, 3))
console.log(cachedComputed(2, 3))
// 只计算了一次
// computed
// 5
// 5