ImmutableJS:将List转换为索引Map

Question

这个问题是关于Immutable.js库的.

我有一个List<T>,哪里T是{name: string, id: number}.我想将其转换为Map<number, T>与id中T的钥匙.使用标准方法toMap给我一个Map顺序索引,并没有办法挂钩.并没有像indexBy或其他方法.怎么做？

Answer 1

你可以使用这样的reducer来做到这一点:

function indexBy(iterable, searchKey) {
    return iterable.reduce(
        (lookup, item) => lookup.set(item.get(searchKey), item),
        Immutable.Map()
    );
}

var things = Immutable.fromJS([
    {id: 'id-1', lol: 'abc'},
    {id: 'id-2', lol: 'def'},
    {id: 'id-3', lol: 'jkl'}
]);
var thingsLookup = indexBy(things, 'id');
thingsLookup.toJS() === {
  "id-1": { "id": "id-1", "lol": "abc" },
  "id-2": { "id": "id-2", "lol": "def" },
  "id-3": { "id": "id-3", "lol": "jkl" }
};