Typescript Finally Block

Typescript finally block

Created By: chatGPT

TypeScript provides a way to handle exceptions using try-catch blocks, and the finally block is a crucial part of this structure. The finally block is executed after the try and catch blocks, regardless of whether an exception was thrown or caught. This feature is particularly useful for cleanup actions, such as closing files or releasing resources.

try {
    // Code that may throw an error
    const result = riskyOperation();
    console.log('Operation succeeded:', result);
} catch (error) {
    // Handle any error that occurred
    console.error('Operation failed:', error);
} finally {
    // Code that will always execute
    console.log('Cleanup actions here.');
}

In this example, the riskyOperation() function may throw an error. If it does, the program will print the error message in the catch block. Regardless of the success or failure of the operation, the finally block will execute, making it ideal for executing cleanup code. Remember that the finally block will execute even if there's a return statement in the try or catch blocks.

try {
    return riskyOperation();
} catch (error) {
    console.log('Operation failed:', error);
    return 'Error';
} finally {
    console.log('This will execute no matter what.');
}

Using the finally block can help prevent resource leaks. For example, if you are working with file systems, you should ensure that files are closed properly whether the operations complete or throw errors. Here's a minimal example of how it can be structured in a TypeScript program.

function readFile() {
    let fileHandle;
    try {
        fileHandle = openFile('path/to/file.txt');
        const data = readFromFile(fileHandle);
        console.log('File data:', data);
    } catch (error) {
        console.error('Error reading file:', error);
    } finally {
        if (fileHandle) {
            closeFile(fileHandle);
            console.log('File closed.');
        }
    }
}