ES6 基础

code/ES6/src/07_set_and_map/01_sets.js

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+// 1. Set 不会使用强制类型转换来判断值是否重复
+let set01 = new Set([1, 2, 3, 4, 5, 5, 5, 5]);
+set01.add("5");
+set01.has("5");
+set01.delete("5");
+set01.clear();
+
+let set02 = new Set(),
+	key1 = {},
+	key2 = {};
+set02.add(key1);
+set02.add(key2);
+console.log(set02.size); // 2
+
+//4.值的遍历
+let set03 = new Set(["hei", "bai", "ying"]);
+set03.forEach(function (value, key, ownerSet) {
+	console.log(key + " " + value);
+	console.log(ownerSet === set03);
+});
+
+// hei hei
+// true
+// bai bai
+// true
+// ying ying
+// true
+
+//5. 在 foreach 中绑定作用域 两种方式
+let Set04 = new Set([1, 2]);
+let processor01 = {
+	output(value) {
+		console.log(value);
+	},
+	process(dataSet) {
+		dataSet.forEach(function (value) {
+			this.output(value);
+		}, this);
+		//如果想在回调函数中使用 this ，你可以给 forEach() 传入一个 this值作为第二个参数
+	}
+};
+processor01.process(Set04);
+
+//使用箭头函数绑定
+let set05 = new Set([1, 2]);
+let processor = {
+	output(value) {
+		console.log(value);
+	},
+	process(dataSet) {
+		dataSet.forEach((value) => this.output(value));
+	}
+};
+processor.process(set05);
+
+//6. 箭头函数转换为数组
+let set06 = new Set([1, 2, 3, 3, 3, 4, 5]),
+	array = [...set06];
+console.log(array); // [1,2,3,4,5]
+
+// 7.对垃圾回收的影响
+let set07 = new Set(),
+	item = {name: "heibaiying"};
+set07.add(item);
+item = null;
+// 将item置为null,其之前所指向的对象 {name: "heibaiying"}仍然不会被垃圾回收，因为其被Set所持有
+console.log([...set07][0]); //{ name: 'heibaiying' }

code/ES6/src/07_set_and_map/02_weak_sets.js

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+//1.与Set区别
+let set = new WeakSet(),
+	key = {};
+// 将对象加入 set
+set.add(key);
+console.log(set.has(key)); // true
+key = null;

code/ES6/src/07_set_and_map/03_maps.js

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+// 1.基本使用
+let map01 = new Map();
+map01.set("name", "Nicholas");
+map01.set("age", 25);
+map01.delete("name");
+map01.clear();
+
+// 2.由数组初始化map
+let map02 = new Map([["name", "Nicholas"], ["age", 25]]);
+console.log(map02.get("name")); // "Nicholas"
+console.log(map02.get("age")); // 25
+console.log(map02.size); // 2
+
+// 3.进行遍历
+let map03 = new Map([["name", "Nicholas"], ["age", 25]]);
+map03.forEach(function (value, key, ownerMap) {
+	console.log(key + " " + value);
+	console.log(ownerMap === map03);
+});

code/ES6/src/07_set_and_map/04_weak_maps.js

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+let key1 = {},
+	key2 = {},
+	map = new WeakMap([[key1, "Hello"], [key2, 42]]);
+console.log(map.has(key1)); // true
+console.log(map.get(key1)); // "Hello"
+console.log(map.has(key2)); // true
+console.log(map.get(key2)); // 42
+map.set({},"123");