Error handling with promises

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When working with promises in JavaScript, it’s important to handle errors appropriately to ensure that your application remains robust and error-free. Here are some techniques for error handling with promises:

Use the catch() method: The catch() method is used to catch any errors that occur during the execution of a promise chain. It takes a callback function as its argument, which is called if any of the promises in the chain are rejected.

asyncFunction()
  .then(result => {
    // Do something with the result
  })
  .catch(error => {
    // Handle the error
  });

Use the finally() method: The finally() method is used to run code after the promise chain has completed, whether it resolved or rejected. This can be useful for cleanup or logging purposes.

asyncFunction()
  .then(result => {
    // Do something with the result
  })
  .catch(error => {
    // Handle the error
  })
  .finally(() => {
    // Do something after the promise chain completes
  });

Throw an error in the promise chain: If an error occurs in the promise chain, you can throw an error to reject the promise and pass the error to the catch() method.

asyncFunction()
  .then(result => {
    if (result === null) {
      throw new Error('Result is null');
    }
    // Do something with the result
  })
  .catch(error => {
    // Handle the error
  });

Return a rejected promise: If an error occurs in the promise chain, you can return a rejected promise to pass the error to the catch() method.

asyncFunction()
  .then(result => {
    if (result === null) {
      return Promise.reject(new Error('Result is null'));
    }
    // Do something with the result
  })
  .catch(error => {
    // Handle the error
  });

By using these techniques, you can ensure that your promises are robust and reliable, and that your application handles errors gracefully.