Clear memory of parent class instance created by calling super/extends

debugcn Published at Dev

Dolly

Good day,

I am facing some memory allocation problem where I have a class Car extending another class CarParent and then creating the instance of Car class somewhere else in the application. But on setting null to car instance is not deleting the instance of parent created because of super keyword.

Class car:

export class Car extends CarParent {
    constructor() {
        super();
    }

    public go(msg: string): string {
        console.log(msg);
        return msg;
    }
}

Class CarParent

class CarParent {
    constructor() {
    }

    getParts() {
        console.log("you will get parts")
    }
}

Inside application:

import { Car } from './car';

class Company {
    config;
    car;
    constructor(config) {
        this.config = config;
        this.car = new Car();
    }

    delete() {
        this.car = null;
        this.config = null;
    }
}

function Config(config) {
    const company: Company = new Company(config);
    return company;
}

export default Config;

On Index.html

<script>
                var config = { place: "france" };
                var box = new Renderer();
                box.delete();
                box = null;
</script>

Tried to debug from heap allocation:

First both Car and CarParent instance created(Screenshot):

After writing box.delete() and box = null and taking snapshot again i can see car instance is deleted:

But CarParent instance does not delete:

I am confused. Why this is happening? Is it correct, whatever happening or how can i delete memory occupied by CarParent.

Please help!

Bergi

the instance of parent created because of super keyword

No, super() does not create a separate instance.

I am confused. Why this is happening?

The CarParent "instance" you are seeing in the heap snapshot is Car.prototype - it's an object inheriting from CarParent.prototype. You can see how it holds the .go method and Car as its .constructor.

You do not want to delete it.

Collected from the Internet

Please contact [email protected] to delete if infringement.

edited at2021-04-8

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