Asynchronous Javascript

Topics covered

1. Synchronous vs asynchronous code
2. How asynchronous code is executed
3. What is the execution thread
4. Event loop
5. Ajax
6. Callback hell
7. Promises object methods
8. Async and await
9. Static and instance Promise methods
10. How response.json() works
11. Error handling with try/catch
12. Interview questions

Promise static methods

Static methods are called directly on the Promise class reference (not on an instance).

Method	Description
Promise.all()	Takes an array of promises; rejects immediately if any one rejects
Promise.allSettled()	Resolves once every promise has settled, regardless of fulfilled/rejected
Promise.any()	Resolves with the first fulfilled promise; order not preserved
Promise.race()	Settles as soon as the first promise settles (fulfilled or rejected)
Promise.reject()	Returns a promise rejected with the given reason
Promise.resolve()	Returns a promise resolved with the given value
Promise.try()	Runs a function and wraps its result/thrown error in a promise
Promise.resolvers()	Returns { promise, resolve, reject } as a convenience object

Folder map

#	Topic	Folder
01	Synchronous vs Asynchronous	01_synchronous-vs-asynchronous
02	Asynchronous behind the scene	02_asynchronous-behind-the-scene
03	Execution thread	03_execution-thread
04	Event loop	04_event-loop
05	Ajax call	05_ajax-call
06	Callback hell	06_callback-hell
07	Promises object method	07_promises-object-method
08	Async vs await	08_async-vs-await
09	Promises static/instance methods (all, allSettled, any, race)	09_promises-methods-example
10	API / response.json()	10_api
11	Error handling with try/catch	11_error-handling-with-try-catch
12	Interview questions	12_interview-questions