斐波拉契数列求第N个；

递归写法：

function fblq(a){
        if(a == 1 || a == 2){
            return 1;
        }else{
            return fblq(a -1) + fblq(a -2);
        }
    }
alert(fblq(6));

非递归：

function fibonacci(n){
            var a,b,res;
            a = b = 1;
            for(var i=3;i<=n;i++){
                res = a + b;
                a = b;
                b = res;
            }
            return res;
        }

        alert(fibonacci(6));