var weakSet1 = new WeakSet();
var obj1 = new Object("obj1");
var obj2 = new Object("obj2");
weakSet1.add(obj1);
weakSet1.add(obj2);
console.log(weakSet1.has(obj1)); // 出力:true
console.log(weakSet1.has(obj2)); // 出力:true
var array = [ obj1, obj2 ];
var weakSet2 = new WeakSet(array);
console.log(weakSet2.has(obj1)); // 出力:true
console.log(weakSet2.has(obj2)); // 出力:true
var weakSetNG1 = WeakSet(); // TypeError 例外 (new なし)
var weakSetNG2 = new WeakSet(123); // TypeError 例外 (オブジェクト以外)
var weakSet1 = new WeakSet();
var obj1 = new Object("obj1");
var obj2 = new Object("obj2");
weakSet1.add(obj1);
weakSet1.add(obj2);
weakSet1.add(123); // TypeError 例外 (オブジェクト以外)
console.log(weakSet1.has(obj1)); // 出力:true
console.log(weakSet1.has(obj2)); // 出力:true
weakSet1.delete(obj2);
console.log(weakSet1.has(obj1)); // 出力:true
console.log(weakSet1.has(obj2)); // 出力:false