Being able to use objects as keys is an important Map feature. Example // Create Objects constapples = {name:'Apples'}; constbananas = {name:'Bananas'}; constoranges = {name:'Oranges'}; // Create a Map constfru
let map1 = new Map(); map1.set('info', {name: 'Jack', age: "26"}); // access the elements of a Map console.log(map1.get('info')); // {name: "Jack", age: "26"} 1. 2. 3. 4. 5. 检查Map 元素 您可以使用 has() 方法检查元素是否在 Map 中。例如, con...
map()does not change the original array. Array Iteration Methods: The Array entries() Method The Array every() Method The Array filter() Method The Array forEach() Method The Array keys() Method The Array map() Method Syntax array.map(function(currentValue, index, arr), thisValue) ...
constmap=newMap([['name','Jean-Luc Picard'],['age',59],['rank','Captain']]);constiterator=map.keys();console.log(iterator);// MapIterator { 'name', 'age', 'rank' }// `map.keys()` returns an iterator, not an array, so you can't// access the values using `[]`iterator[...
We have a map of stones. The keys are integers and the values are strings. let stones = new Map(); An empty map is created. stones.set(0, "citrine"); A new key/value pair is inserted with set. console.log(stones.get(0)); We get the value which has key equal to 0. ...
Double each element in the array Copy let numbers = [1, 4, 9] let doubles = numbers.map(function(num) { return num * 2/*w w w .j av a 2 s.com*/ }) console.log(numbers); console.log(doubles); Get the full name for each person in the array: ...
除了Object类型之外,Array类型恐怕是js中最常用的类型了,并且随着js的发展进步,数组中提供的方法也越来越来,对数组的处理也出现了各种骚操作。 如果对js原型/原型链不了解的可以移步_深入了解javascript原型/原型链,_下面我们就来一起学习下js的数组。
// references an ArcGIS Online item pointing to a Map Service Layer let layer = new MapImageLayer({ portalItem: { // autocasts as esri/portal/PortalItem id: "8444e275037549c1acab02d2626daaee" } }); map.add(layer); // adds the layer to the map Sublayers Map services contain one...
graphics GraphicsLayer Provides access to the Map's GraphicsLayer. graphicsLayerIds String[] An array of the current GraphicsLayers in the map. height Number Current height of the map in screen pixels. id String Reference to HTML DIV or other element where the map is placed on the page. in...
Map数据结构,它类似于对象,也是键值对的集合,但是“键”的范围不限于字符串,各种类型的值(包括对象)都可以当作键。 13.Object.assign(对象的拷贝) Object.assign() 方法用于将所有可枚举属性的值从一个或多个源对象复制到目标对象。它将返回目标对象。 代码语言:javascript 代码运行次数:0 运行 复制 const target...