Async await – nested then depending on result of previous await

Async await – nested then depending on result of previous await

When working with asynchronous code in TypeScript, the async/await syntax provides a more readable and structured way to handle promises. However, there may be situations where you need to nest multiple then blocks depending on the result of a previous await statement. In this blog post, we will explore different solutions to handle such scenarios in TypeScript.

Solution 1: Using if statements

One way to handle nested then blocks is by using if statements to conditionally execute code based on the result of the previous await statement. Here’s an example:

async function fetchData() {
  try {
    const result1 = await fetch('https://api.example.com/data');
    if (result1.ok) {
      const data1 = await result1.json();
      // Process data1
    } else {
      // Handle error for result1
    }

    const result2 = await fetch('https://api.example.com/other-data');
    if (result2.ok) {
      const data2 = await result2.json();
      // Process data2
    } else {
      // Handle error for result2
    }

    // Continue with other async operations
  } catch (error) {
    // Handle any errors that occurred during the async operations
  }
}

fetchData();

In this example, we use if statements to check if the result.ok property is true or false. Depending on the result, we either process the data or handle the error accordingly.

Solution 2: Using switch statements

Another approach to handle nested then blocks is by using switch statements. This can be useful when you have multiple possible outcomes and want to handle each case differently. Here’s an example:

async function fetchData() {
  try {
    const result = await fetch('https://api.example.com/data');
    switch (result.status) {
      case 200:
        const data = await result.json();
        // Process data
        break;
      case 404:
        // Handle not found error
        break;
      case 500:
        // Handle server error
        break;
      default:
        // Handle other cases
        break;
    }

    // Continue with other async operations
  } catch (error) {
    // Handle any errors that occurred during the async operations
  }
}

fetchData();

In this example, we use a switch statement to handle different cases based on the result.status property. Depending on the case, we can process the data or handle specific errors.

Both of these solutions provide a structured way to handle nested then blocks in TypeScript using async/await. Choose the solution that best fits your specific use case and coding style.

That’s it for this blog post! We hope you found these solutions helpful in handling nested then blocks with async/await in TypeScript. If you have any questions or suggestions, feel free to leave a comment below.

Happy coding!