TS类型后的尖括号包含两个数据是什么意思

Question

const state: UserState = {
  permissions: []
};

const getters: GetterTree<UserState, any> = {
  permissions(state): Permission[] {
    return state.permissions;
  }
};

其中<UserState, any>的作用是什么

Answer 1

ts的泛型

interface GetterTree<T, K>  {
    // ...
}

然后 T 对应着 UserState ，K 对应着 any