Problem extending native (es6) classes in Safari

user_1530590 0
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I'm having trouble extending the native WebSocket class using es6 classes.

The following piece of code works on Chrome and Firefox, but not on Safari:

class MyWebSocket extends WebSocket {
    doSomething() {
        console.log('hi');
    }
}

let ws = new MyWebSocket('wss://127.0.0.1:4000');
ws.doSomething();

TypeError: ws.doSomething is not a function. (In 'ws.doSomething()', 'ws.doSomething' is undefined)

console.log('MyWebSocket.prototype') lets me see that the function was added to the prototype. This happens with a few other builtin classes, Animation being one, but not with others, like Date for example.

Has anyone run into this? Is this a bug in Safari? Any advice is appreciated!

es6-class ecmascript-6 safari prototype javascript
1 Answers

Yes, looks like a bug. The WebSocket constructor is probably hardcoded to return a WebSocket instance. It doesn't respect Symbol.species either.

As a workaround you could use something like this:

class MyWebSocket extends WebSocket {
    constructor(url) {
        super(url);
        Object.setPrototypeOf(this, MyWebSocket.prototype);
    }
user_9891210
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