What are some examples of promise chaining in TypeScript?

What are some examples of promise chaining in TypeScript?

Promise chaining in TypeScript allows you to execute asynchronous operations in sequence. For example, you can fetch data from an API, process it, and then save it to a database, all in a chain.

Can you show me a code example?

Sure! Here's a simple example:

function fetchData(): Promise<string> {
    return new Promise((resolve) => {
        setTimeout(() => resolve('Data fetched!'), 1000);
    });
}

function processData(data: string): Promise<string> {
    return new Promise((resolve) => {
        setTimeout(() => resolve(data + ' Processed!'), 1000);
    });
}

fetchData()
    .then(processData)
    .then((result) => console.log(result)); // Outputs: Data fetched! Processed!

What happens if one of the promises fails?

If a promise in the chain fails, the subsequent promises will be skipped. You can handle errors using .catch(). For example:

fetchData()
    .then(processData)
    .catch((error) => console.error('Error:', error));