What's so great about JavaScript Promises?

What’s so great about JavaScript Promises?

“Promises” represent the next great paradigm in JavaScript programming. But understanding why they are so great is no simple matter. At its core, a Promise represents the result of a task, which may or may not have completed. The only interface requirement of a Promise is having a function called then, which can be given callbacks to be called when the promise is fulfilled or has failed

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