JS 分步实现柯里化函数

https://blog.youkuaiyun.com/weixin_34329187/article/details/91396617

function currying(fn) {
  let args_arr = [], max_length = fn.length
  let closure = function (...args) {
    // 先把参数加进去
    args_arr = args_arr.concat(args)
    // 如果参数没满，返回闭包等待下一次调用
    if (args_arr.length < max_length) return closure
    // 传递完成，执行
    return fn(...args_arr)
  }
  return closure
}
function add(x, y, z) {
  return x + y + z
}
curriedAdd = currying(add)
console.log(curriedAdd(1, 2)(3))