https://github.com/siddhesh-coder/promise-apis

https://github.com/siddhesh-coder/promise-apis

Last synced: about 2 months ago
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• Host: GitHub
• URL: https://github.com/siddhesh-coder/promise-apis
• Owner: siddhesh-coder
• Created: 2023-11-22T14:11:14.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2024-04-08T18:11:37.000Z (9 months ago)
• Last Synced: 2024-04-08T22:04:57.452Z (9 months ago)
• Language: JavaScript
• Size: 85 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Promise-APIs

## 1. Promise.all([])

- It takes an array of promises as an input "iterable".

- Example: `Promise.all([p1, p2, p3])`.

### Success Case:

- Suppose `p1`, `p2`, `p3` take time `3s`, `1s`, `2s` to complete. If all get resolved, it will 

  give the result in the array `[val1, val2, val3]`.

- Time taken: It will take 3s (because `p1` takes the most time 3s).

- It will wait for all of them to finish.

### Reject Case:

- Suppose after 1s, `p2` gets rejected. As soon as any of the promises get rejected, `Promise.all` 

  will throw an immediate error of that same failed promise.

- It will not wait for other promises.

## 2. Promise.allSettled([])

- If you have no problem with even promise being rejected, then use this. (you want both the cases 

  to happen)

- If `p2` gets rejected, wait for all promises to settle. After 3s, the output will be `[{val1}, 

  {err2}, {val3}]`.

## 3. Promise.race([])

- This races between all the promises whichever of them gets settled first, the promise will give 

  the success or failure based on the race winning promise.

- Example: `Promise.race([p1, p2, p3])` for time `3s`, `2s`, `4s`. In this case, `2s` will settle 

  first.

## 4. Promise.any([])

- It will wait for the first success, searching for the first success.

## Note:

- If all fail, it will throw an `AggregateError`, and if you want an array of errors `[err1, err2, 

  err3]`, then use `console.log(err.errors)`.

## Meaning of Settled:

![Local Image](Screenshot%20(180).png)