如何從 map 中計算 boolean 值

Question

使用的框架是 Angular 8

我有一個名為teams的數組，我可以通過使用teams.length來獲取其長度。 現在，對於每個計數， teams都有一個名為teamInfo的 map。 這個 teamInfo map 再次有一個 boolean 值isClosed可以通過teams.teamInfo.isClosed為每個計數訪問，當它 json 到 ngforloop 時，這是

*ngFor=" let teamID of JSObject.keys(teams); trackBy: trackByFn

<app-team-card
[team]="teams[teamID]"
[isClosed]="teams[teamID].teamInfo.isClosed">
</app-team-card>

我的目標是獲取所有具有isClosed =true. 我的嘗試是

getClosedTeams(teams) {
         let closedTeams = teams.teamInfo.filter((isClosed) => {
             return isClosed.select == true;
        });
        console.log(closedTeams.length);
    }

Answer 1

您可以使用.reduce執行以下操作：

 const team01 = new Map(); team01.set('name', 'team-01'); team01.set('isClosed', false); const team02 = new Map(); team02.set('name', 'team-02'); team02.set('isClosed', true); const team03 = new Map(); team03.set('name', 'team-01'); team03.set('isClosed', true); const teams = [team01, team02, team03]; function getClosedTeamsCount (teams) { return teams.reduce((acc, teamInfo) => { return Number(teamInfo.get('isClosed')) + acc; }, 0) } console.log(getClosedTeamsCount(teams));