红宝书第十四讲:详解JavaScript集合类型:Map、Set、WeakMap 资料取自《JavaScript高级程序设计(第5版)》。 查看总目录:红宝书学习大纲 一、Map:钥匙任选的“保险箱” Map的键可以是任意数据类型(如对象、函数),不像普通Object只能用字符串/符号作为键。适合需
ObjectMap Not directly iterableDirectly iterable Do not have a size propertyHave a size property Keys must be Strings (or Symbols)Keys can be any datatype Keys are not well orderedKeys are ordered by insertion Have default keysDo not have default keys ...
Leaflet|©OpenStreetMapcontributors Here we create a map in the'map'div, addtiles of our choice, and then add a marker with some text in a popup: varmap = L.map('map').setView([51.505, -0.09],13); L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', { attribut...
MapView|SceneView The view associated with the UI components. UI width Number The width of the UI container. UI Property Details components Property components String[] An array of strings representing the default widgets visible when a MapView or SceneView is created. The default widgets diff...
dataset 属性是一个 DOMStringMap 的实例,包含一组键/值对映射 # 插入标记 innerHTML 属性 在读取 innerHTML 属性时,会返回元素所有后代的 HTML 字符串,包括元素、注释和文本节点。而在写入 innerHTML 时,则会根据提供的字符串值以新的 DOM 子树替代元素中原来包含的所有节点。如果赋值中不包含任何 HTML 标签,...
2.some 对数组中每一项运行给定函数,如果函数对任一项都返回true,则返回true3.filter 对数组中每一项运行给定函数,返回该函数会返回true的项组成的数组4.forEach 对数组每一项运行给定函数,无返回值5.map 对数组每一项运行给定函数,返回每次函数调用返回结果组成的数组// 归并方法 reduce和reduceRight(和前者遍历的...
Only supported in 2D MapViews. The default value is the following: { type: "simple-fill", style: "solid", color: [150, 150, 150, 0.2], outline: { color: [50, 50, 50], width: 0 } } activeTool Property activeTool String |null |undefinedreadonly Since: ArcGIS Maps SDK fo...
A primer on L.CRS.Simple, how to make maps with no concept of “latitude” or “longitude”.WMS and TMSHow to integrate with WMS and TMS services from professional GIS software.Working with map panesHow the default map panes work to display overlays on top of tiles, and how to override...
constfruits =newMap([ ["apples",500], ["bananas",300], ["oranges",200] ]); Try it Yourself » Learn more about Map objects, and the difference between a Map and an Array, in the the chapter:JavaScript Maps. JavaScript Sets
Why? Minimizes diff churn when adding or removing arguments. // bad [1, 2, 3].map(x => x * x); // good [1, 2, 3].map((x) => x * x); // bad [1, 2, 3].map(number => ( `A long string with the ${number}. It’s so long that we don’t want it to take up...