A job queue in two lines of JS

If you need a job queue in JS, you can do it in two lines:

type Job = () => Promise<unknown>;

let chain = Promise.resolve();
const enqueue = (job: Job) => chain = chain.then(job, job);

For example, if your app makes API requests, you may need requests to be processed in the order they were dispatched:

function setDone(id: string, done: boolean) {
  enqueue(() => fetch(`/todos/${id}`, {
    method: "POST",
    body: JSON.stringify({ done }),
  }));
}

Note that chain.then(job) is probably not what you want, because any rejection in the chain will cause the job to never run. Instead you want chain.then(job, job), which will run job when the chain either rejects or resolves.

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