颜色显示异常的问题 #4

/**
* nth element in the fibonacci series.
* @param n >= 0
* @return the nth element, >= 0.
*/
function fib(n) {
    var a = 1, b = 1;
    var tmp;
    while (--n >= 0) {
        tmp = a;
        a += b;
        b = tmp;
    }
    return a;
}

document.write(fib(10));