curry.js

const curry = fn => function innerCurry(...args) {
    return args.length >= fn.length ? fn(...args) : innerCurry.bind(null, ...args);
}

const foo = curry((a, b, c) => a + b + c);

foo(1, 2, 3); // 6
foo(1)(2, 3); // 6
foo(1, 2)(3); // 6
foo(1)(2)(3)  // 6