Promises in JavaScript
In JavaScript, a Promise is an object denoting the final completion—or failure—of an asynchronous operation together with the resultant value. It is a method of handling asynchronous code more in line with synchronous behavior.
How Promises Manage Asynchronous Operations
- Cleaner code: Promises assist prevent the feared "callback hell" that can arise with layered callbacks.
- Error handling: With the catch() method, they offer a disciplined approach to manage mistakes.
- Chaining: Then() methods let you chain several asynchronous operations together.
- State management: One of three states—pending (starting state), fulfilled (operation done successfully), or rejected—can represent the promise of state management.
Example:
JavaScript
function fetchData(url) {
return new Promise((resolve, reject) => {
// Simulate an asynchronous operation
setTimeout(() => {
if (/* data fetched successfully */) {
resolve(data);
} else {
reject(error);
}
}, 1000);
});
}
fetchData('https://api.example.com/data')
.then(data => {
console.log(data);
})
.catch(error => {
console.error(error);
});
Here, fetchData generates a promise. Should the data retrieval prove successful, the then block runs. Should a mistake exist, the catch block manages it.
Promises help you create asynchronous code that is simpler to manage, grasp, and develop.
Related :
Answered 3 months ago
Anonymous
Promises in JavaScript
In JavaScript, a Promise is an object denoting the final completion—or failure—of an asynchronous operation together with the resultant value. It is a method of handling asynchronous code more in line with synchronous behavior.
How Promises Manage Asynchronous Operations
Example:
JavaScript
Here, fetchData generates a promise. Should the data retrieval prove successful, the then block runs. Should a mistake exist, the catch block manages it.
Promises help you create asynchronous code that is simpler to manage, grasp, and develop.
Related :