Typescript Promises

Typescript promises

Created By: chatGPT

Promises in TypeScript are a way to handle asynchronous operations. A promise represents a value that may be available now, or in the future, or never. It can be in one of three states: pending, fulfilled, or rejected.

const myPromise = new Promise((resolve, reject) => {
    // Simulating an asynchronous operation
    setTimeout(() => {
        const success = true;
        if (success) {
            resolve('Operation was successful!');
        } else {
            reject('Operation failed!');
        }
    }, 1000);
});

You can use the then method to handle a fulfilled promise and the catch method to handle a rejected promise. This allows you to work with the result of the asynchronous operation conveniently.

myPromise
    .then(result => {
        console.log(result); // Will log: Operation was successful!
    })
    .catch(error => {
        console.error(error);
    });

TypeScript provides a way to specify the type of value the promise will return. This makes it easier to work with the promise's result within your application by providing type safety.

const stringPromise: Promise<string> = new Promise((resolve) => {
    resolve('Hello, TypeScript!');
});

You can also use the async/await syntax with promises to make your code cleaner and easier to read. By marking a function as async, you can use the await keyword to wait for a promise to resolve.

const asyncFunction = async () => {
    try {
        const result = await myPromise;
        console.log(result); // Will log: Operation was successful!
    } catch (error) {
        console.error(error);
    }
};

asyncFunction();

Using Promise.all allows you to execute multiple promises in parallel, and it returns a single promise that resolves when all of the promises have fulfilled or one has rejected.

const promise1 = Promise.resolve('First promise');
const promise2 = Promise.resolve('Second promise');

Promise.all([promise1, promise2])
    .then((results) => {
        console.log(results); // Will log: ['First promise', 'Second promise']
    })
    .catch((error) => {
        console.error(error);
    });