How Can I Construct A Infinite Fun()()()...()() In Javascript?

Just a curious question. I want to create a function can handle infinite 'layer'? make add(2)(3), add(1)(2)(3)...(10) all works. Any ideas?

Solution 1:

You can, with a slight catch. The return value must be a function that you can coerce to a number. Here's how:

functionadd (addend) {
  'use strict'const sum = (this || 0) + addend
  const chain = add.bind(sum)

  for (const prop ofObject.getOwnPropertyNames(Number.prototype)) {
    chain[prop] = Number.prototype[prop].bind(sum)
  }

  return chain
}

console.log(add(1))
console.log(add(1)(2))
console.log(add(1)(2)(3))
// convinced yet?let four = add(4)
console.log(typeof four, four === 4)
// it's a function, not a number, so coerce to a primitive first
four = Number(four)
console.log(typeof four, four === 4)

add() is a function that contains its context (this) and all the Number.prototype properties, including its Symbol.toPrimitive property. In strict mode, the context behaves a lot more nicely, allowing you to define it as a primitive value like a number instead of defaulting to window and coercing bound primitives to Objects.