函数柯里化

function getSum(a, b, c) {
    return a + b + c;
}

function curry(fn) {
    return function curryFn(...args) {
        console.log(fn.length);
        if (args.length < fn.length) {
            return function() {
                console.log('arguments===', args.concat(Array.from(arguments)))
                return curryFn(...args.concat(Array.from(arguments)));
            }
        }
        return fn(...args);
    }
}

let curryGetSum = curry(getSum);
console.log(curryGetSum(1, 2, 3));
console.log(curryGetSum(1)(2, 3));
console.log(curryGetSum(1)(2)(3));