Using Catch in JavaScript

In JavaScript, error handling is commonly done using the try...catch statement. The try block lets you test a block of code for errors, while the catch block lets you handle the error. Here are a few examples that demonstrate how to use catch to handle errors in different scenarios:

1. Basic try...catch

try {
    // Code that may throw an error
    let result = someFunction();
    console.log(result);
} catch (error) {
    // Code to run if an error occurs
    console.log('An error occurred:', error.message);
}

2. Catch with Finally

finally is an optional block that will execute after the try and catch blocks, regardless of whether an error was thrown or not. It’s often used for cleaning up resources.

try {
    // Code that may throw an error
    let data = riskyOperation();
    console.log(data);
} catch (error) {
    // Handle errors
    console.error('Error:', error.message);
} finally {
    // Cleanup code, runs whether or not an error occurred
    console.log('Operation complete.');
}

3. Catch with Error Logging

This example demonstrates logging the error for further investigation while notifying the user in a general manner.

try {
    // This function might fail
    performCriticalTask();
} catch (error) {
    console.error('Error logged:', error);
    // Notify user in a user-friendly manner
    alert('Something went wrong. Please try again later.');
}

4. Catch with Specific Error Types

Sometimes you might want to handle different types of errors differently. This can be done by checking the type of the error.

try {
    // This function might throw several types of errors
    processUserInput(input);
} catch (error) {
    if (error instanceof TypeError) {
        console.error('Type Error:', error.message);
    } else if (error instanceof RangeError) {
        console.error('Range Error:', error.message);
    } else {
        console.error('Unexpected Error:', error.message);
    }
}

5. Async/Await with Try-Catch

When working with asynchronous code, you can use try...catch to handle errors in promises.

async function fetchData() {
    try {
        const response = await fetch('https://api.example.com/data');
        const data = await response.json();
        console.log(data);
    } catch (error) {
        console.error('Failed to fetch data:', error.message);
    }
}

These examples should give you a good starting point on how to handle errors in various scenarios using JavaScript’s try...catch mechanism.