https://github.com/elazzouzihassan/javascript-promises
Welcome to the JavaScript Promises README! This document provides an overview of JavaScript Promises
https://github.com/elazzouzihassan/javascript-promises
async await ecmascript es6 javascript promises
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Welcome to the JavaScript Promises README! This document provides an overview of JavaScript Promises
- Host: GitHub
- URL: https://github.com/elazzouzihassan/javascript-promises
- Owner: ElazzouziHassan
- Created: 2023-12-14T15:37:08.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2023-12-14T17:10:34.000Z (over 1 year ago)
- Last Synced: 2025-02-28T22:50:31.798Z (4 months ago)
- Topics: async, await, ecmascript, es6, javascript, promises
- Language: JavaScript
- Homepage:
- Size: 4.88 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
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README
# JavaScript Promises :
Promises are a feature in JavaScript that allow you to work with asynchronous code in a more organized and readable way. They represent the eventual completion or failure of an asynchronous operation and provide a cleaner alternative to using callbacks.
## Creating Promises :
You can create a new Promise using the Promise constructor. It takes a function as an argument, which in turn takes two parameters: resolve and reject.
```bash
const myPromise = new Promise((resolve, reject) => {
// Asynchronous operation
const success = true;
if (success) {
resolve("Operation successful!");
} else {
reject("Operation failed!");
}
});
```
## Promise States :
A Promise can be in one of three states:
- **Pending**: The initial state, neither fulfilled nor rejected.
- **Fulfilled**: The operation completed successfully.
- **Rejected**: The operation failed.
## Handling Promises :
You can handle the results of a Promise using the then and catch methods.
```bash
myPromise
.then((result) => {
console.log(result); // Operation successful!
})
.catch((error) => {
console.error(error); // Operation failed!
});
```
## Chaining Promises :
Promises can be chained together, making it easier to handle multiple asynchronous operations sequentially.
```bash
const promise1 = new Promise((resolve) => {
resolve("First operation complete");
});
const promise2 = (message) => {
return new Promise((resolve) => {
resolve(`${message}, Second operation complete`);
});
};
promise1
.then((result) => {
return promise2(result);
})
.then((result) => {
console.log(result);
});
```
## Example: Fetching Data :
A common use case for Promises is handling asynchronous operations like fetching data from an API.
```bash
function fetchData(url) {
return new Promise((resolve, reject) => {
fetch(url)
.then((res) => {
if (!res.ok) {
throw new Error(`HTTP error! Status: ${res.status}`);
}
return res.json();
})
.then((data) => {
resolve(data);
})
.catch((error) => {
reject(error);
});
});
}
// Example usage
fetchData("https://jsonplaceholder.typicode.com/todos/1")
.then((data) => {
console.log(data);
})
.catch((error) => {
console.error(error);
});
```
---
-by @Elazzouzi Hassan (Wizardy - 🧙♂️)