然后在promise外声明变量，然后在promise中初始化，然后访问promise

Question

I need to access outState var which declared outSide class and then has set inside getData() func within promise then() func.

inside usrs func when loop has finished I need to access that but I cant.

let outState = {};
class A extends Component{
  getData(usr){
    db.collection('a/'+usr+'/bb').get().then(snap=>{
      for(i = snap.docs.length-1; i>=0; i--){
         outState[usr] = [...outState[usr], snap.docs[i].data()];
      }
    });
  }

  usrs(usrs){
    for(i = usrs.length-1; i>=0; i--){

       this.getData(usrs[i]);
       if(i===0){
        this.setState({ ...this.state, ...outState });
       }

    }
  }
}

I need to update state outside for loop, otherwise I can set the state inside promise func but It makes slow my app. Just I want to access it outside promise then function and then outside of loop update it.

Answer 1

I would recommend refactoring your component to something approximately like this, to keep everything a bit cleaner:

class A extends Component{
  constructor() {
    super();
    this.state = {
      usersData: {}      
    }  
  }

  getData(usr){
      let dataForUser = {};
      db.collection('a/'+usr+'/bb').get().then(snap=>{
        for(i = snap.docs.length-1; i>=0; i--){
           dataForUser[usr] = [...dataForUser[usr], snap.docs[i].data()];
        }
      });
      return dataForUser;
    }

    usrs(usrs){
      let data = {};
      for(i = usrs.length-1; i>=0; i--){
         let userData = getData(usrs[i]);

         if(i===0){
          data = {...data, ...userData};
         }
      }
      this.setState({usersData: data});
    }
  }