rate = tip == 3 ? [1, 1.25, 1.5, 2, 2.5, 3] : [1, 1.25, 1.5];
这个是三目运算符啊
就是当tip 等于 3 则rate 赋值为[1, 1.25, 1.5, 2, 2.5, 3] ,tip 不等于 3 则rate 赋值为 [1, 1.25, 1.5];
等同于
if (tip == 3)
rate = [1, 1.25, 1.5, 2, 2.5, 3];
else
rate = [1, 1.25, 1.5];
如有帮助,望采纳!谢谢!