📝 finally runs before return

If you have a return statement somewhere within your try or catch block inside a function. It will still execute the finally block of that try-catch group before actually returning from the function.

I recently encountered this pattern when working with Claude where it was closing a database connection in the finally block, even though it was returning a value from the try block. I thought this would leave dangling database connections, but turns out that is not the case.

Take this function as an example:

const getUserName = (userId) => {
    console.log('Entered function body');
    try {
        console.log('Entered try block');
        if (typeof userId === 'string') {
            console.log('Entered a string userId');
            throw `${userId} is not a valid userId`;
        } else {
            console.log('Returning username');
            return `username-${userId}`;
        }
    } catch (e) {
        console.log('Entered catch block. Caught:', e);
        return 'nope';
    } finally {
        console.log('Entered finally block');
    }
};

When returning from the try block:

console.log('Value returned from function:', getUserName(123));
// The above function call prints these logs
// Entered function body
// Entered try block
// Returning username
// Entered finally block
// Value returned from function: username-123

When returning from the catch block:

// Returning from the `catch` block
console.log('Value returned from function:', getUserName('blah'));
// The above function call prints these logs
// Entered function body
// Entered try block
// Entered a string userId
// Entered catch block. Caught: blah is not a valid userId
// Entered finally block
// Value returned from function: nope