Calling JSON.parse from a function returns Undefined

Question

I need to store a JSON in a variable. I have the next function:

retrieve(){
    JSON.parse(localStorage.getItem('todos'));
}

And i'm trying to store the return of the function in the variable.

this.todos = this.retrieve()

But I'm getting:

model.js:5 Uncaught TypeError: Cannot read property 'retrieve' of undefined

If i do this instead, it works:

this.todos = JSON.parse(localStorage.getItem('todos'));

Why is that happening?

Edit: Full code

export default class Model {

constructor(){
    this.view = null;
    this.todos = this.retrieve();
    if(!this.todos || this.todos.length < 1){
        this.todos = [
            {
                id: 0,
                title: 'default',
                description: 'default',
                completed: false,
            }
        ]
        this.id = 1;
    }
    this.id = this.todos[this.todos.length - 1].id + 1;

    retrieve(){
         return JSON.parse(localStorage.getItem('todos'));
    }

}

Thanks everyone.

you need to return something from a function if you want it to return something — Jaromanda X
– Jaromanda X, Commented Jul 4, 2021 at 12:25
@JaromandaX Actually I tried returning but the outcome was the same so I was just trying without the return and other ways. — Space guy
– Space guy, Commented Jul 4, 2021 at 12:32
It depends on where are you executing this this.todos = this.retrieve()? My be inside an regular function instead of arrow function. — Rajdeep D
– Rajdeep D, Commented Jul 4, 2021 at 12:38
@RajdeepDebnath retrieve() is a class method. this.todos is in the constructor of the class. — Space guy
– Space guy, Commented Jul 4, 2021 at 12:41
retrieve() shouldn't be in the constructor, you want it as a method of the class — charlietfl
– charlietfl, Commented Jul 4, 2021 at 12:59

Rajdeep D · Accepted Answer · 2021-07-04 13:03:34Z

Your class level methods should be outside the constructor.

localStorage.setItem('todos', JSON.stringify([{id:1},{id:2},{id:3}]))

class Model {

constructor(){
    this.view = null;
    this.todos = this.retrieve();
    if(!this.todos || this.todos.length < 1){
        this.todos = [
            {
                id: 0,
                title: 'default',
                description: 'default',
                completed: false,
            }
        ]
        this.id = 1;
    }
    this.id = this.todos[this.todos.length - 1].id + 1;

}



    retrieve(){
         return JSON.parse(localStorage.getItem('todos'));
    }
}

console.log(new Model());

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