const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

// Email validation function
const validateEmail = (email) => {
  return emailRegex.test(email);
}

// Usage example
const email = "example@example.com";
const isValidEmail = validateEmail(email);
if (isValidEmail) {
  console.log("Valid email format.");
} else {
  console.log("Invalid email format.");
}

In the above code, emailRegex is the regular expression that represents the email address format. The regular expression is enclosed in /.../, where ^ represents the start of the string and $ represents the end of the string. [^\s@]+ represents one or more non-space and non-@ characters, and \. represents the . character.

The validateEmail function is used to check if an email address is valid. It uses the test function to match the emailRegex with the provided email address. The result is stored in the isValidEmail variable, which can be used to determine the validity of the email address.