不定长柯里化

[Twlig]

题目：柯里化sum(1)(2,3)()，实现不接受参数时才调用

function sum(...args) {
    let allArgs = [].concat(args)
    function curry(..._args) {
        allArgs = allArgs.concat(_args)
        return _args.length !== 0 ? curry : allArgs.reduce((pre, cur) => pre + cur, 0)
    }
    return args.length !== 0 ? curry : allArgs.reduce((pre, cur) => pre + cur, 0)
}