Math.E

function compoundOneYear(interestRate, currentVal) {
  return currentVal * Math.E ** interestRate;
}

console.log(Math.E);
// Expected output: 2.718281828459045

console.log((1 + 1 / 1000000) ** 1000000);
// Expected output: 2.718280469 (approximately)

console.log(compoundOneYear(0.05, 100));
// Expected output: 105.12710963760242

function getNapier() {
  return Math.E;
}

getNapier(); // 2.718281828459045