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collection.js
60 lines (43 loc) · 1.26 KB
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collection.js
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// map
var myMap = new Map();
var keyObj = {},
keyString = "a string";
myMap.set(keyString, "a");
myMap.set(keyObj, "b");
myMap.size; // 2
myMap.get(keyString); // "a"
myMap.get(keyObj); // "b"
myMap.get("a string"); // "a"
myMap.get({}); // undefined, keyObj !== {}
for (var [key, value] of myMap) {
console.log(key + " = " + value);
}
for (var key of myMap.keys()) {
console.log(key);
}
myMap.forEach(function(value, key) {
console.log(key + " = " + value);
}, myMap)
//set
var set = new Set('aaabb');
console.log(set); // Set {"a","b"}
var s = new Set('123');
s.add('1').add(1).add({a:1}).add({a:1});
console.log(s); // Set {"1", "2", "3", 1, Object {a: 1}, Object {a: 1}}
// WeakMap
var wm = new WeakMap();
wm.set(s, { extra: 42 });
wm.size === undefined //true
//WeakSet
var ws = new WeakSet();
ws.add({ data: 42 });
// Because the added object has no other references, it will not be held in the set
var ws = new WeakSet();
var obj = {};
var foo = {};
ws.add(window);
ws.add(obj);
ws.has(window); // true
ws.has(foo); // false, foo has not been added to the set
ws.delete(window); // removes window from the set
ws.has(window); // false, window has been removed