Promises in JavaScript are a powerful mechanism for handling asynchronous operations. They allow us to perform actions when an asynchronous task is completed or when an error occurs. The catch method is an essential part of handling errors in promises.

What is the catch method?

The catch method is used to handle any errors that occur during the execution of a promise. It is called when a promise is rejected, either by throwing an error inside the promise, or by explicitly rejecting it using the reject function.

Syntax

The catch method is appended to a promise chain and takes a single parameter, which is a function that will be called with the error object as an argument.

promise.then((result) => {
  // Perform some action with the result
}).catch((error) => {
  // Handle the error
});

Example

Let’s see an example of how to use the catch method in promises:

const fetchData = () => {
  return new Promise((resolve, reject) => {
    // Simulating an error by throwing an exception
    throw new Error('Unable to fetch data');
  });
};

fetchData()
  .then((data) => {
    console.log('Data fetched:', data);
  })
  .catch((error) => {
    console.error('Error:', error.message);
  });

In the above code, we have a fetchData function that returns a promise. We intentionally throw an error inside the promise to simulate an error condition. We then chain the catch method to handle the error and log the error message to the console.

Conclusion

The catch method is a crucial part of handling errors in promises. It allows us to gracefully handle any errors that occur during the execution of asynchronous operations. By properly using the catch method, we can write more robust and error-resilient code.

For more information on promises and error handling, you can refer to the MDN web docs on Promises and Error handling with promises.

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