How to use this in a constructor with TypeScript?

Question

What is a good approach to giving this a type annotation 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.

Elaboration

My editor shows me red squiggly lines beneath each use of the this keyword in this constructor. I get a [ts] warning that this does not have any type annotation.

How should I go about adding type annotation to this?

Not clear with your question Can you little bit elaborate it ? — CodeChanger
– CodeChanger, Commented Jan 30, 2019 at 12:09
@CodeChanger: Thanks for trying to help. Let me know if my elaboration still is not clear enough — user1283776
– user1283776, Commented Jan 30, 2019 at 12:14

Paleo · Accepted Answer · 2019-01-30 12:19:39Z

2

The type of this can be defined as a fake parameter, in first position:

function Client(this: any, options: ClientOptions) {
    // ...
}

Or, this kind of error can be disabled by setting the compiler option --noImplicitThis to false.

answered Jan 30, 2019 at 12:19

Paleo

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Suxino · Accepted Answer · 2019-01-30 12:20:38Z

0

Since you are using typescript you could use Class instead of this approach. There you wont have any errors with using this.xxx And as a bonus you will get type hinting when using the class

answered Jan 30, 2019 at 12:20

Suxino

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