js求公约数

Question

function gyy(m,n){

            
            var r=m%n;                
                m=n;
                n=r;
            if(r==0){
                return m;
            }else{
            
            gyy(m,n);
            
            }
        }
        alert(gyy(6,12))

上面的代码为什么我输出是undefined？

Answer 1

    function gyy(m, n) {
        var r = m % n;
        m = n;
        n = r;
        if (r == 0) {
            return m;
        } else {
            return gyy(m, n);
        }
    }
    console.log(gyy(6, 12));