<script>

//需求：獲取斐波那契數列的前n項陣列

function fib(num) {

var arr = [];

if(num == 1){

return arr = [1];

}else if(num == 2){

return arr = [1,1];

}else{

arr = [1,1];

var a=1;

var b=1;

var c=2;

var arrlen =arr.length;

for(var i=2;i<num;i++){

arr.push(c);

a=b;

b=c;

c=a+b;

}

return arr;

}

}

alert( fib(1)); // 1

alert( fib(2)); // 1,1

alert( fib(3)); // 1,1,2

alert( fib(4)); // 1,1,2,3

alert( fib(5)); // 1,1,2,3,5

alert( fib(8)); // 1,1,2,3,5,8,13,21

</script>