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What does promise resolve do and what would you use it for?
resolve() method in JS returns a Promise object that is resolved with a given value. Any of the three things can happened: If the value is a promise then promise is returned. If the value has a “then” attached to the promise, then the returned promise will follow that “then” to till the final state.
Are Promises asynchronous?
Using Promises Note: Promises are asynchronous. Promises in functions are placed in a micro-task queue and run when other synchronous operations complete.
What are the advantages of promises?
Benefits of Promises
- Improves Code Readability.
- Better handling of asynchronous operations.
- Better flow of control definition in asynchronous logic.
- Better Error Handling.
Do I have to resolve a promise?
A promise is just an object with properties in Javascript. There’s no magic to it. So failing to resolve or reject a promise just fails to ever change the state from “pending” to anything else. This doesn’t cause any fundamental problem in Javascript because a promise is just a regular Javascript object.
Which is better, caching or memoizing promise results?
In order words, caching promise objects makes sense (e.g. caching web request promises), but caching promise results is built-in and happens automatically. So to that end, it’d be smarter to add caching at a higher level.
Can a promise be cached in JavaScript code?
Code looks fine – but it strikes me as somewhat unnecessary. A promise can only be resolved/rejected once, so if you just keep the promise object itself around, its result is automatically cached within.
When to use promise object in JavaScript code?
It won’t re-do whatever caused it to be resolved/rejected. So just keep the promise object itself around and you can use it whenever you want. In order words, caching promise objects makes sense (e.g. caching web request promises), but caching promise results is built-in and happens automatically.
How to memoize promise results in JavaScript?
One approach is to chain cachedPromise and “regular”, thus, if cachedPromise fails, we call a regular one (and caching results). The second is to have a wrapper function, something like a decorator in python, and being able to wrap any promise-returning function when needed.