JavaScript Promise in 100 Seconds

Key Takeaways

a promise represents a value that is unknown now that may become known in the future in other words in asynchronous value think of it like a ride hailing app when you request a ride the driver makes a promise to pick you up while you're waiting the ride is pending in the future if all goes according to plan the driver will resolve to pick you up then take you somewhere at which point your ride has been fulfilled but in some cases the driver might reject your ride in which case you'll need to catch one somewhere else either way the original request is now finally settled as a developer he might want to create a promise to represent an asynchronous value but more often than not you'll be consuming promises to use the result of an asynchronous operation in your code on the Left we're making promises on the right we're using them when constructed a promise starts off in a pending state it's your job to define a callback function called an executor that defines when to resolve or reject the promise this is where you would kick off your asynchronous work on the other side the consumer of the promise has called it's then method it's waiting for the asynchronous value to be fulfilled when that happens it will call this function with the value as its argument we fulfill the promise by calling resolve but there's always the possibility of an exception in that case we can reject the promise and send the error back down to the consumer which can use the catch method and an entirely different function for handling exceptions and if you just want to run some code no matter what you can use finally to handle both possibilities all of these methods return promises which means they can be chained together to handle multiple asynchronous operations in a row this has been JavaScript promises in 100 seconds thanks for watching and also make sure to follow my brand new Instagram account for even more content on this topic I will see you in the next one [Music]