Discussion on: Interview Question Journey - Currying, Closures, Type Coercion, oh my 😱

[Nicolas Marcora]

Nice one! I agree this is a very weird interview question to be asking, but since we're already doing crazy stuff, you inspired me to go further. This version can accept multiple numbers or callbacks at once, and will add/apply all to the count.

const add = (...args) => {
    let count = 0

    const applyArguments = args => args.reduce((acc, arg) => {
        if (typeof arg === 'function') return arg(acc)
        if (typeof arg === 'number') return acc + arg
        return acc
    }, count)

    const adder = (...args) => args[0] === undefined
        ? count
        : (count = applyArguments(args), adder)

    adder.valueOf = () => count

    return adder(...args)
}


const double = n => n * 2

const timesTen = n => n * 10

add(1, 2, 3)(double)(10)(timesTen, double)(2)()
// 442

+add(1, 2, 3)(double)(10)(timesTen, double)(2)
// 442

add(10)(double) + add(20)(timesTen)
// 220

[Eugene Karataev]

Thanks for sharing, I like how you go deeper with add functionality.