Javascript object oriented programming showing undefined

Question

I am new to javascript oop i have been trying to get the desired value but it gives me undefined

class person {
  constructor(isGreat, brain, personality) {
    this.isGreat = isGreat;
    this.brain = brain;
    this.personality = personality;
  }
  getDetails(req) {
    this.req = req;

    let dic = {
      isGreat: this.isGreat,
      brain: `they have ${this.brain} brain`,
      personality: `they have ${this.personality} personality`,
    };

    return dic.req;
  }
}

let person0 = new person(true, "massive", "great");
console.log(person0.getDetails("isGreat"));

req can get read but dic.req shows undefined

The problem is console.log shows undefined.

apparently you are not assigning `dic.req` anywhere, did you mean to do `return dic[req];` ? — Mauro Aguilar, Aug 01 '22 at 19:07
JavaScript object oriented programming cannot possibly show undefined. It’s just a paradigm, not a concrete program. — user3840170, Aug 01 '22 at 19:14

score 1 · Accepted Answer · answered Aug 01 '22 at 19:08

dic doesn't have a req property. If you want to get a property whose name is stored in req variable, use the following syntax:

dic[req]

Just like accessing array members. In fact, a.b and a['b'] are equivalent in JavaScript.

BTW: The assignment this.req = req is not necessary.

louisi9 · Answer 2 · 2022-08-01T19:12:41.833

0

You are returning the req property of your object, not the property with the key stored inside req. You need to use square brackets to get the index stored inside req.

return dic[req]

This is because it gets parsed as dic['isgreat'] rather than dic['req'].

edited Aug 01 '22 at 19:12

answered Aug 01 '22 at 19:11

louisi9

26
2

Javascript object oriented programming showing undefined

2 Answers2