Leveraging object imported from interface

I have a question regarding Angular/TypeScript. It may seem obvious, but I would like clarification.

What I'm doing is creating an interface and exporting it:

export interface MainObject {
  location: string;
  methodType: string;
  securityLevel: string;
  provider: string;
}

Then, I import it into a component and create an empty object:

public descriptorCreateFinal: MainObject

When attempting to assign a value to the object:

descriptorCreateFinal.location = 'someString';

An error occurs stating that 'location' is not declared.

However, if I declare the object like this:

public descriptorCreateFinal: MainObject = {
    location: '',
    methodType: '',
    securityLevel: '',
    provider: '',
}

I can assign a value to 'descriptorCreateFinal.location' without any issues.

My question is, do I really need to set values for all variables in the object during the declaration stage?

Answer №1

Statement

descriptorCreateFinal: MainObject

This particular code block serves as a declaration for an object, without actually initializing it. As a result, the object remains undefined until a value is assigned to it.

Creation

As you may have observed, once an object is assigned, it functions as intended:

descriptorCreateFinal: MainObject = {
    location: '',
    methodType: '',
    securityLevel: '',
    provider: '',
}

Shortcut to Initialization

In addition, these shortcuts can also be used, based on the level of type enforcement in your TypeScript project:

const descriptorCreateFinal = {} as MainObject

const descriptorCreateFinal = {} as Partial<MainObject>

Optional Approach

Consider employing a class over an interface, depending on the requirements of your project. A class allows for instantiation using the 'new' keyword, while an interface is more lightweight as it is removed during transpilation to JavaScript.

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