[英]How can I search for an object property value in an array if I only know a different property?
[英]How Can I Count Object's in Array With Given Property Value (Angular-FirebaseRealtime)
当它为真时,我想计算“状态”。 我怎样才能 ?
组件.ts
getAttDetails(ıd){
this.afAuth.user.subscribe(user => this.serviceCourses.getAttDetails(ıd,user).subscribe(detail => console.log(detail)));
}
服务课程
getAttDetails(ıd,user:firebase.User){
return this.db.list('/denemeDersler/'+ıd+'/attendance/'+user.uid).snapshotChanges().pipe(map(changes => changes
.map(c => ({key: c.payload.key, ...c.payload.val()}))));
}
你可以做这样的事情
假设您的数据集是这样的
let arr = [{key : '2020-01-15', statu : true},{key : '2020-01-11', statu : true},{key : '2020-01-10', statu : false}] let count = 0; arr.map(item=> { if(item.statu === true){ count++ } }) console.log(count) // output : 2
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