デフォルトパラメータ

by yshrkn

JavaScript

function sayHello(toSomeone) {
 var someone = toSomeone || "こんにちは、名無しさん！";

 if (toSomeone) {
  console.log("こんにちは、" + toSomeone + "さん！");
 } else {
 	console.log(someone);
 }

}

sayHello("目黒");
sayHello();