Access own properties in Javascript constructor?

Question

I've got a class, something like this:

class Server {
    constructor() {
        this.server = http.createServer(function (req, res) {
            this.doSomething()
        });
    }

    doSomething() {
        console.log("Working")
    }
}

I want to call my doSomething() function from inside the constructor, how can I do this? I've tried doing this.doSomething() and doSomething(), both say they are not a function. Also, say in the constructor I did console.log(this.someValue), it logs undefined. How can I access the classes own properties/methods? Is it even possible? Thanks.

this.doSomething() will call it. If you get an error, post the code that produces that error — Yousaf
– Yousaf, Commented May 11, 2021 at 18:45
I have now found the issue, the this is referring to the callback function on the HTTP server. Is there a way I can almost "go up 1 level" with this keyword? — Yankue
– Yankue, Commented May 11, 2021 at 18:51
use an arrow function: http.createServer((req, res) => { ... } — Yousaf
– Yousaf, Commented May 11, 2021 at 18:54

Nisala · Accepted Answer · 2021-05-12 05:23:29Z

1

As Yousaf said, all you need to do is use an arrow function instead. Here's an example that shows this in action, using setTimeout instead of http.createServer:

class Server {
    constructor() {
        this.server = setTimeout(() => {
            this.doSomething();
        }, 0);
    }

    doSomething() {
        console.log("Working");
    }
}

new Server();

answered May 12, 2021 at 5:23

Nisala

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Adrian · Accepted Answer · 2021-08-31 19:00:29Z

1

class Server {
    constructor() {
        const _this = this;
        this.server = http.createServer(function (req, res) {
            _this.doSomething()
        });
    }

    doSomething() {
        console.log("Working")
    }
}

answered Aug 31, 2021 at 19:00

Adrian

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