let map = new Map([["k1", "v1"], ["k2", "v2"], ["k3", "v3"]]); console.log(map instanceof Map); // true console.log(map); // Map(3) {"k1" => "v1", "k2" => "v2", "k3" => "v3"} </script> 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 对于键是对...
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...
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 constfruits =newMap(); ...
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) ...
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。
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: ...
克隆 map 就像将Map.entries()转换成数组一样简单: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 // `clone` is now a separate map that contains the same keys/values// as `map`.constclone=newMap(Array.from(map.entries)); 扩展
// 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...
portalUrl = "https://myHostName.esri.com/arcgis"; const webmap = new WebMap({ portalItem: { // autocasts as new PortalItem() id: "f701172599f04ea8781de2a4adzz46ab" } }); Then you must reference the WebMap instance in the map property of the view. const view = new MapView...
let map = new Map();map.set('1', 'str1'); // a string keymap.set(1, 'num1'); // a numeric keymap.set(true, 'bool1'); // a boolean key// remember the regular Object? it would convert keys to string// Map keeps the type, so these two are different:alert( map.get(1)...