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// Basic Namespace Example
// In a browser or non-module environment, TypeScript namespaces compile to JavaScript objects

// This simulates how a namespace would be compiled in JavaScript
var Validation;
(function (Validation) {
  // Private to the namespace (closure)
  const lettersRegexp = /^[A-Za-z]+$/;
  
  // Exported class
  Validation.LettersValidator = class LettersValidator {
    isValid(s) {
      return lettersRegexp.test(s);
    }
  };
  
  // Another exported class
  Validation.ZipCodeValidator = class ZipCodeValidator {
    isValid(s) {
      return /^[0-9]+$/.test(s) && s.length === 5;
    }
  };
})(Validation || (Validation = {}));

// Using the namespace members
let letterValidator = new Validation.LettersValidator();
let zipCodeValidator = new Validation.ZipCodeValidator();

// Testing the validators with various inputs
console.log("Testing LettersValidator:");
console.log(`"Hello" is valid: ${letterValidator.isValid("Hello")}`);
console.log(`"Hello123" is valid: ${letterValidator.isValid("Hello123")}`);
console.log(`"123" is valid: ${letterValidator.isValid("123")}`);

console.log("\nTesting ZipCodeValidator:");
console.log(`"12345" is valid: ${zipCodeValidator.isValid("12345")}`);
console.log(`"1234" is valid: ${zipCodeValidator.isValid("1234")}`);
console.log(`"ABCDE" is valid: ${zipCodeValidator.isValid("ABCDE")}`);

// Note: In TypeScript, you cannot access the non-exported lettersRegexp
console.log("\nIn TypeScript, you cannot access non-exported members:");
console.log("// Validation.lettersRegexp would be an error");

Testing LettersValidator:
"Hello" is valid: true
"Hello123" is valid: false
"123" is valid: false

Testing ZipCodeValidator:
"12345" is valid: true
"1234" is valid: false
"ABCDE" is valid: false

In TypeScript, you cannot access non-exported members:
// Validation.lettersRegexp would be an error