What is the proper way to implement this in a TypeScript constructor?

What is the recommended method for providing a type annotation to this in a constructor?

function Client(options: ClientOptions) {
    const defaultOptions = { 
        host: 'ws://127.0.0.1',
        port:  8080,
        logger: function() {
            const prefix = "LOG:";
            console.log.call(null, prefix, ...Array.from(arguments))
        },
        maxTime: 30000, 
        startFromTransactionId: 1
    };

    Object.assign(this, { ...defaultOptions, ...options });

    this.transactionsCounter = 0;
    this.requestCallbacks = {};
    this.socket = null;
}

[ts] 'this' implicitly has type 'any' because it does not have a type annotation.

Explanation

I noticed that my text editor highlights each instance of using the this keyword in this constructor. There is a [ts] warning indicating that no type annotation is provided for this.

Could you advise me on how to properly add a type annotation to this?

Answer №1

The nature of the variable this can be specified as a placeholder parameter, positioned at the beginning:

function User(this: any, settings: UserSettings) {
    // ...
}

Alternatively, this type of issue can be resolved by toggling the compiler option --noImplicitThis to true.

Answer №2

If you're working with TypeScript, consider leveraging Classes instead of the current method. This will eliminate any potential errors related to using "this.xxx", plus provide type hinting for added clarity.

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