一个方法同时满足 sum(2,3)=== sum(2)(3)

箭头函数

let sum=(...n)=>{
	if(n.length===2){
			return n[0] + n[1]
	}else{
			return (m)=>n[0]+m
	}
}
console.log(sum(2,3));
console.log(sum(2)(3))

普通函数

 function sum() {
            var som = arguments;
            if (som.length === 2) {
                return som[0] + som[1];
            } else {
                return function(n) {
                    return som[0] + n
                }
            }
        };
        console.log(sum(2,3));
		console.log(sum(2)(3))