ES6 and variable scope inside a promise

Question

Not sure what I'm missing here.

I need to get the output of data into this.contact. Right now, I'm using a static class variable, but it seems dirty to have to do that.

export class contactEdit {
  static t; // static class var
  constructor() {
    this.id = null;
    this.contact = null;
    contactEdit.t = this;
  }

  activate(id) {
    this.id = id;
    let contact = this.contact; // scoped version of class var
    return dpd.contacts.get(id).then(function(data) {
      console.log(data);
      contactEdit.t.contact = data; // this works
      contact = data; // this doesn't
    });
  }
}

Normally I would create a var contact inside the activate() function (it works in the Chrome console) but this doesn't seem to working in ES6.

Chrome console:

var c = null;
undefined
c;
null
dpd.contacts.get('a415fdc8f5a7184d').then(function(data) {
      c = data;
    });
Object {}fail: (n)then: (e,t)__proto__: Object
c;
Object {firstName: "John", lastName: "Doe", id: "a415fdc8f5a7184d"}

Answer 1

You need to do two things. First, use an arrow function, and second, use `this.contact = data;

activate(id) {
  this.id = id;
  return dpd.contacts.get(id).then(data => {
    console.log(data);
    this.contact = data;
  });
}

You use an arrow function because it deals with JavaScript's "this" issue, where this refers to the lexical scope of the function, and not the object you're currently in. Using an arrow function makes sure that this outside the arrow function is the same as this inside the arrow function.

You need to use this.contact because contact is an instance property of the class.