How to properly describe an object in a TypeScript model?

Question

JavaScript

Hello! I just started learning TypeScript and when describing the types used in the model, an error occurs, namely "Object literal may only specify known properties, and 'value' does not exist in type '{ [key: number]: any; }'"...
how to correctly set the type of the _total object and its internal values?

export default class Model {

    _total: { [key: number]: any } = {};

    constructor() {
        super();
        this._total= {
            value: 1,
            btn: {
                add: true,
                rem: false
            }
        };
    }
}

Answer 1

Well, your _total key is not a number, it's a string
UPD: here it is described about the index signature https://basarat.gitbooks.io/typescript/docs/types/...

Answer 2

export default class Model {
    _total: { [key: string]: any } = {};

    constructor() {
        super();
        this._total['value'] = 1;
        this._total['btn'] = {
                add: true,
                rem: false
        };
    }
}

If you turn everything into any, then there will be no sense from typescript. So it's better to type your properties like this

class Total {
    value: number,
    btn: {
        add: boolean,
        rem: boolean
    }
};

export default class Model {
    _total: Total;

    constructor() {
        super();
        this._total= new Total {
            value: 1,
            btn: {
                add: true,
                rem: false
            }
        };
    }
}