Wrap Promises in a Synchronous Function
In this case, we can encapsulate the logic of checking a Promise’s state synchronously within a function. This function can return a value or trigger specific actions based on the Promise’s state.
Example: In this example, we will see how to synchronously determine a JavaScript Promise’s state by wrapping the promise inside a function.
Javascript
function checkPromiseState(promise) { return promise .then(() => "fulfilled" ) . catch (() => "rejected" ); } const myPromise = new Promise((resolve, reject) => { setTimeout(() => { resolve( "Success!" ); }, 1000); }); checkPromiseState(myPromise) .then(state => { console.log(`Promise state: ${state}`); }); |
Explanation
- The checkPromiseState function encapsulates a Promise, resolving to “fulfilled” on success and “rejected” on error.
- An example Promise, myPromise, simulates an asynchronous task using setTimeout.
- The code invokes checkPromiseState on myPromise and logs the resulting state: “fulfilled” or “rejected,” indicating the Promise’s resolution.
Output:
Promise state: fulfilled
How to Synchronously determine a JavaScript Promise’s State
Handling asynchronous operations in JavaScript can be challenging. However, Promises has made this task easier by providing a more elegant and better error management solution. Although Promise-based code is primarily designed to work asynchronously, there may be instances where you need to synchronously determine a Promise’s state for various reasons. In this article, we’ll explore how to do just that.
A Promise represents a value that might not be available yet but will be at some point in the future. It has three states:
- Pending: It is the state when the Promise is created and hasn’t been resolved or rejected yet.
- Fulfilled: The Promise has successfully resolved with a value.
- Rejected: The Promise has encountered an error or exception during its execution of code.
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