In what ways can beginner PHP developers improve existing scripts by focusing on functionality first before refactoring for optimization?

Beginner PHP developers can improve existing scripts by focusing on functionality first before refactoring for optimization by ensuring that the code works correctly and meets the desired requirements. This involves identifying any bugs or errors in the script and fixing them before moving on to optimize the code for performance.

// Example code snippet demonstrating focusing on functionality first
// before refactoring for optimization

// Function to calculate the sum of an array of numbers
function calculateSum($numbers) {
    $sum = 0;
    foreach ($numbers as $number) {
        $sum += $number;
    }
    return $sum;
}

// Test the function with an array of numbers
$numbers = [1, 2, 3, 4, 5];
echo "The sum of the numbers is: " . calculateSum($numbers);