function extractNumbers(text) {
  // Matches integers and decimals. Allows for optional leading sign.
  const numberRegex = /-?\d+(\.\d+)?/g;
  const matches = text.match(numberRegex);
  return matches ? matches.map(Number) : [];
}

// Example usage:
// const text1 = "Item price is $12.50, quantity is 3. Total: 37.5. Negative value: -5.";
// console.log(extractNumbers(text1)); // [12.5, 3, 37.5, -5]
// const text2 = "No numbers here!";
// console.log(extractNumbers(text2)); // []