您还可以考虑将自定义迭代器添加到您的 Set 或 Map 中: const mySet = new Set([1, 2, 3, 4, 5]); const myMap = new Map([ [1, 'one'], [2, 'two'], [3, 'three'], [4, 'four'], [5, 'five'] ]); const customIterator = function () { // get the values from the Set...
WeakMap 是一种键值对的集合,其中的键必须是对象或非全局注册的符号,且值可以是任意的 JavaScript 类型,并且不会创建对它的键的强引用。换句话说,一个对象作为 WeakMap 的键存在,不会阻止该对象被垃圾回收。一旦一个对象作为键被回收,那么在 WeakMap 中相应的值便成为
letmap =newMap(); map.set("1-1","foo"); map.set("0-1","bar"); map.set("2-1","baff");console.log(map) Output: bash Map(3) { '1-1' => 'foo', '0-1' => 'bar', '2-1' => 'baff' } Thenew Map()creates the empty Map, and theset()function insert newkey-value...
set(`c`, 3); // Map(2) {"a" => 1, "b" => 2, "c" => 3} const autoConvertMapToObject = (map) => { const obj = {}; for (const item of [...map]) { const [ key, value ] = item; obj[key] = value; } return obj; } const obj = autoConvertMapToObject(map) l...
最后,Map还有更优雅、实用和可靠的APIs,大家可以按需取用,记住要不是兼容性考虑,Map以及Set还可以被挖掘出更多的用法。 1Use Maps More and Objects Lessbuilder.io/blog/maps 2When You Should Prefer Map Over Object In JavaScriptzhenghao.io/posts/objec 3structuredClone() - Web APIs | MDNdeveloper.mozill...
For a map to be visible to the user in the DOM, a MapView must be created and reference a minimum of two objects: a Map instance and a DOM element. Each is set in the map and container properties respectively. // Create a MapView instance (for 2D viewing) const view = new MapVie...
var myMap = new Map(); myMap.set("key1", "value1"); myMap.set("key2", "value2"); myMap.set("key3", "value3"); console.log(myMap.size); Output 3 Summary JavaScript Map object allows us to store key/value pairs, and to obtain their size, we can make use of the siz...
本文基于Vue 3.2.30版本源码进行分析为了增加可读性,会对源码进行删减、调整顺序、改变部分分支条件的操作,文中所有源码均可视作为伪代码由于ts版本代码携...
，如果用于遍历对象的话还会遍历原型上的键。因此不再建议使用，很多 eslint 配置默认对 for...in ...
main (mdn/translated-content#4205) 3 people authored Feb 22, 2022 Verified 1 parent 6ae7209 commit e592ee7 Showing 2 changed files with 147 additions and 279 deletions. Whitespace Ignore whitespace Split Unified files/es/web/javascript/reference/global_objects/weakmap index.html ...