Currying is about decomposing a function taking multiple arguments into numerous functions with single arguments. It is named after Haskell Curry.

curry.js

const curry = fn => {
    if (fn.length === 0) {
        return fn;
    }

    const _curry = (...args) => {
        if (fn.length <= args.length) {
            return fn.apply(null, args);
        }
        return _curry.bind(null, ...args);
    }

    return _curry;
}

const add = (a,b,c,d) => a + b + c + d;

curry(add)(1,2)(3)(4); // 10