✏️1.1 자, 시작해보자!

리팩토링 할 예시 코드

function statement(invoice, plays) {
  let totalAmount = 0;
  let voluemCredits = 0;
  let result = `청구 내역(고객명): ${invocie.customer})\n`;
  const format = new Intl.NumberFormat("en-US", 
                                       { style: "currency", currency: "USD", 
                                        minimumFractionDigits: 2 }).format;
  
  for (let perf of invoice.performaces) {
    const play = plays[perf.playID];
    let thisAmount = 0;
    
    switch (play.type) {
      case "tragedy":
        thisAmount = 40000;
        if (perf.audience > 30) {
          thisAmount += 1000 * (perf.audience - 30);
        }
        break;
      case "comedy":
        thisAmount = 30000;
        if (perf.audience > 20) {
          thisAmount += 1000 + 500 * (perf.audience - 20);
        }
        thisAmount += 300 * perf.audience
        break;
      default:
        throw new Error(`알 수 없는 장르: ${play.type}`);
      }
	  
    // 포인트를 적립한다
    volumeCredits += Math.max(perf.audience - 30, 0);
    // 희극 관객 5명마다 추가 포인트를 제공한다.
    if ("comedy" === play.type) volumeCredits += Math.Floor(perf.audience / 5 );
    
    // 청구 내역을 출력한다.
    result += ` ${play.name}: ${format(thisAmount/100)} (${perf.audience}석)\n`;
    totalAmount += thisAmount;
  }
  result += `총액: ${format(totalAmount/100)}\n`;
  result += `적립 포인트: ${volumeCredits}점\n`;
  return result;
}