Example Analysis of waiting for Promises in js

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Wait for Promises

In some cases, we need to wait for multiple Promise to finish, and here we use Promise.all.

Const PromiseArray = [Promise.resolve (100), Promise.reject (null), Promise.resolve ("Data release"), Promise.reject (new Error ('Something went wrong'))]; Promise.all (PromiseArray) .then (data = > console.log (' all resolved! here are the resolve values:', data)) .catch (err = > console.log ('got rejected! reason:', err)

One thing to note about Promise.all is that when a Promise rejects, this method throws an error. This means that our code will not wait until all the Promise is complete.

If you want to wait until all the Promise is complete, whether they are rejected or successful, you can use Promise.allSettled. This method is in the final version of ES2020.

Const PromiseArray = [Promise.resolve (100), Promise.reject (null), Promise.resolve ("Data release"), Promise.reject (new Error ('Something went wrong'))]; Promise.allSettled (PromiseArray) .then (res = > {console.log (res);}) .catch (err = > console.log (err)) / / {status: "fulfilled", value: 100}, / / {status: "rejected", reason: null}, / / {status: "fulfilled", value: "Data release"}, / / {status: "rejected", reason: Error: Something went wrong.} / /] Thank you for reading! This is the end of this article on "sample Analysis of waiting for Promises in js". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!