Part 5: Asynchronous Programming with TypeScript

Section 5: Asynchronous Programming with TypeScript

In this section, we will dive into asynchronous programming with TypeScript. Asynchronous operations are essential for handling time-consuming tasks, such as network requests or file I/O, without blocking the execution of other code. We will explore promises, async/await syntax, error handling, and working with async functions.

Promises

Promises are a way to handle asynchronous operations and represent the eventual completion (or failure) of an operation. They provide a clean and structured approach to working with asynchronous code.

function fetchData(): Promise<string> {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      const data = 'Data received'
      resolve(data)
    }, 2000)
  })
}

fetchData()
  .then((data) => {
    console.log(data) // Data received
  })
  .catch((error) => {
    console.error(error)
  })

Promises allow us to chain asynchronous operations and handle both success and error scenarios effectively.

Async/Await

Async/await is a syntax that simplifies working with promises and makes asynchronous code appear more synchronous. It provides a more straightforward and readable way to handle asynchronous operations.

function fetchData(): Promise<string> {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      const data = 'Data received'
      resolve(data)
    }, 2000)
  })
}

async function getData(): Promise<void> {
  try {
    const data = await fetchData()
    console.log(data) // Data received
  } catch (error) {
    console.error(error)
  }
}

getData()

The await keyword allows us to pause the execution of an async function until a promise is resolved or rejected. It simplifies the control flow and error handling of asynchronous code.

Error Handling

Error handling is crucial in asynchronous programming to ensure that errors are properly caught and handled. Promises and async/await provide mechanisms to handle errors effectively.

function fetchData(): Promise<string> {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      const error = new Error('Data retrieval failed')
      reject(error)
    }, 2000)
  })
}

fetchData()
  .then((data) => {
    console.log(data)
  })
  .catch((error) => {
    console.error(error) // Data retrieval failed
  })

Using try/catch with async/await, we can also handle errors within the async function itself.

Working with Async Functions

Async functions are a shorthand syntax for defining functions that return promises. They make asynchronous code more readable and easier to write.

async function getData(): Promise<string> {
  const data = await fetchData()
  return data
}

getData()
  .then((data) => {
    console.log(data)
  })
  .catch((error) => {
    console.error(error)
  })

Async functions provide a convenient way to structure and write asynchronous code without dealing explicitly with promises.

Conclusion

Asynchronous programming is a fundamental aspect of modern web development, and TypeScript provides excellent support for handling asynchronous operations. Promises and async/await syntax enable us to write clean and maintainable asynchronous code. By mastering these concepts, we can build responsive and efficient applications.

In the next section, we will dive into advanced TypeScript topics, including decorators, type definitions for third-party libraries, and best practices for writing TypeScript code.