js 求前n项的 fibnaci 数列和

    function f(n) {
        var num1 = 1,
            num2 = 1;
        if (n == 1)
            document.write(num1);//n=1,输出1
        else if (n > 1) {
            document.write(num1 + " " + num2 + " ");//n>=2;先输出前2项
            for (var i = 3; i < n; i++) {
                var result = num1 + num2;
                document.write(result + " ");
                num1 = num2;
                num2 = result;
            }
        }

    }
    f(3);