Reference Error: object not defined when trying to initialize a map in a class

Question

Hi im trying to initialize two maps as object in a class:

class Keyboard {

    keys;
    events;

    constructor() {
        keys = {};
        events = {};
    }

}

The variable keys works fine, but on events = {}; this happens:

Uncaught ReferenceError: events is not defined
at new Keyboard (Keyboard.js:8:16)
at app.js:20:14

I can't figure out why would keys works and events not, even if I change their order.

just use this before access the class properties.

Mohit Sharma
– Mohit Sharma

2022-07-18 14:13:56 +00:00
Commented Jul 18, 2022 at 14:13 — Mohit Sharma
– Mohit Sharma, Commented Jul 18, 2022 at 14:13

Mina · Accepted Answer · 2022-07-18 14:12:57Z

1

Both shouldn't work, you need to add this, to refer to the object properties.

class Keyboard {

    keys;
    events;

    constructor() {
        this.keys = {};
        this.events = {};
    }

}

const keyboard = new Keyboard()

console.log(keyboard)

answered Jul 18, 2022 at 14:12

Mina

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3 Comments

Crih.exe Over a year ago

but, why do keys works?

Mina Over a year ago

No, it shouldn't work, in my code example, if you removed this in both, you will see the same error happen to keys, check please.

Crih.exe Over a year ago

There was already an another variable named keys on another js file. thanks

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