TypeScript:
文字列の補間

let user = 'Yamada';
let message = `こんにちは、${user}さん！`;
console.log(message); // "こんにちは、Yamadaさん！"

let price = 1500;
let taxRate = 0.1;
let total = `合計: ${price * (1 + taxRate)}円`;
console.log(total); // "合計: 1650円"

// ES5以前の例
let user = 'Yamada';
let message = 'こんにちは、' + user + 'さん！';
console.log(message);

function totalPrice(price: number, taxRate: number): string {
  return `合計: ${price * (1 + taxRate)}円`;
}

console.log(totalPrice(1500, 0.1)); // "合計: 1650円"