Undefined array with initialization oninit

Question

I have this snippet:

usersTempList=[];

ngOnInit() {
  this.obj = {user: JSON.parse(localStorage.userDetails),room:"Sala" + this.projectID, projectID: this.projectID};
  this.loggedUser = JSON.parse(localStorage.userDetails).UserID;
  this.roomList.push(this.obj.room);
  this.usersTempList=[];
  console.log("Initialized array")
  this.join(this.obj);
  ...
}

join(obj: any){
    this.socket.emit("join",obj,this.getOnline);
}

getOnline(err,msg){
  console.log(this.usersTempList);
  console.log("Printed array");
  this.usersTempList = JSON.parse(JSON.stringify(msg));
  console.log("qwerty",this.usersTempList);
}

Opening this component on the browser, neither *ngFor works (it isn't printing anything) and, the console.log of the first line of getOnline always prints undefined. Also, even that the variable is updated in the subsequent lines, *ngFor still doesn't update the interface.

Does anyone have any clue about this?

Thanks!

Please share your HTML code, and first of all here, getOnline is a function which is not returning anything. — Ushma Joshi
– Ushma Joshi, Commented Mar 14, 2019 at 10:39
could you also further specify the output you would want to see? — Axelle
– Axelle, Commented Mar 14, 2019 at 10:42

Supertramp · Accepted Answer · 2019-03-14 14:06:35Z

1

The problem was solved, it happened because I couldn't access my array inside my scope, so I used an arrow function and it worked, usersTempList wasn't undefined anymore..

join(obj: any){
  this.socket.emit("join",obj, (err,msg) => {      
        this.usersTempList=JSON.parse(JSON.stringify(msg))
    });
}

Thank you all!

edited Mar 14, 2019 at 14:06

answered Mar 14, 2019 at 12:53

Supertramp

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