Anticipate the completion of Subject callback execution

Take a look at the code snippet below:

const mA = async () => {
    try {
        const subscription = myEmitter.subscribe(url => getD(url));
        const la=()=>{...};
        return la;
    }
     catch (error) {
        throw error;
    }
};

What steps can be taken to ensure that the code following const subscription is executed only after getD has completed?

Answer №1

It seems like your question is a little unclear, but I believe I have grasped the gist of what you are trying to achieve.

Before proceeding, it's crucial to verify that myEmitter has a finite nature, meaning it will not run indefinitely. For instance, if you define myEmitter = interval(1000), subscribing to it will result in an endless loop, preventing any actions from being executed "after" it.

If we assume that myEmitter behaves finitely, you can easily utilize the Observable.toPromise method. Since your code is already within an async function, the revised snippet would look like this:

const mA = async () => {
    try {
        const url = myEmitter.toPromise();
        getD(url); // remember to await this operation
        const la=()=>{...};
        return la;
    }
     catch (error) {
        throw error;
    }
};

Note: It's worth mentioning that the usage of toPromise is currently deprecated. Additional information on this matter can be found in this informative blog post.

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