A promise is a proxy for a value not necessarily known when the promise is created It allows you to associate handlers with an asynchronous action's eventual success value or failure reason. Here is how to use a promise Promise.then () takes two arguments, a callback for success and another for failure Both are optional, so you can add a callback for success or failure only To demonstrate the use of promises, we will use the callback examples from the previous chapter:
The meaning of promise is a declaration that one will do or refrain from doing something specified How to use promise in a sentence. Or, there are fairy tale promises, regrettable and problematic at the time, they must be honored And lastly, there are election promises, commitments that most people realize will later be shaped by politics and compromise Both an oath and an affirmation can be a promise One special kind of promise is the vow.
Think of a promise as a placeholder for a value that will be available in the future. Promises are the foundation of asynchronous programming in modern javascript They make it easier to express and reason about sequences of asynchronous operations without deeply nested callbacks, and they support a style of error handling that is similar to the synchronous try.catch statement. A promise is an object representing the eventual completion or failure of an asynchronous operation Here are just some of president trump’s promises made, promises kept Stopping the migrant invasion promise made
“we will close the border. To get some relief, you promise to send it to them when it’s published You give your fans a list They can fill in their email addresses, so that when the song becomes available, all subscribed parties instantly receive it. To tell someone that you will certainly do something If something promises to be good…
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