是排行榜的需求，数据长这样

[
{name:"q", week:[{index:19, number:2},{index:20,number:4}]},
{name:"w", week:[{index:19, number:2},{index:20,number:3}]},
{name:"e", week:[{index:19, number:2},{index:20,number:5}]}
]

比如这周是第20周，我就要找到week里index为20的，然后根据index为20的number来从大到小排序，这个应该怎么写呢？