ES 6個人メモ——WeakSetデータ構造


 Set  ,     
1.WeakSet        ,          
2.WeakSet         ,
	         WeakSet       
    :              ,
 		                      ,
 		            WeakSet  
// 1.
const ws = new WeakSet();
// ws.add(1);	// Invalid value used in weak set
//       j            ,  ES6  WeakSet    
// 1.[1,2]      
const a = [[1,2],[3,4]];
const ws2 = new WeakSet(a);
for(let i of a){
     
	console.log(i)
}
const b = [3,4];
// const ws3 = new WeakSet(b)	//Invalid value used in weak set

//   
/*
	add(value),delete(value),has(value)
 */
// eg
const ws4 = new WeakSet();
const obj = {
     };
const foo = {
     };

ws4.add(obj);

console.log(ws4.has(obj),ws4.has(foo),ws4.size);

// eg2
const foos = new WeakSet();
class Foo {
     
	constructor(){
     
		foos.add(this);
	};
	method(){
     
		if(!foos.has(this)){
     
			throw new TypeError('Foo.protoType.method   Foo      !');
		}
	}
}