我认为你应该在typescript中创建一个这样的映射，你错过了构造函数调用。您现在所拥有的只是一个对象字面...
Map不是原语，需要用构造函数来调用(我认为Typescript应该对此进行警告)。
Could you put a quick demo of your code together on stackblitz so I can take a look and debug this? The tooltip is implemented via a mapLabel, I suspect this is a timing issue where the label has not yet been added to the map, so the getMap() function has not been added to the...
.set("A",1) .set("B",2) .set("C",3); 我们还可以用键-值对数组初始化映射 let map = new Map([ [ "A", 1 ], [ "B", 2 ], [ "C", 3 ] ]); 我们可以通过get方法获取Map对象的值 map.get("A"); // 1 还可以通过has方法判断是否有这个键名 map.has("A"); // true 通过d...
Issue description or question Hello, I ran into a problem while testing out the new es2019 features. I get an error when I try to use the flatMap method Sample code const nestedWords = [['one', 'two', ['three']] const flatten = nestedWor...
x。在javascript中：null?.length !== 0和undefined?.length !== 0为真。所以这个条件：...
It is a very common use case to need the own values of an object - for example, when using an object as a hash filter. Many libraries have a “values” function: lodash/underscore, jQuery, Backbone, etc. It is also useful to obtain an array of key/value pairs (what the spec calls...
Uncaught TypeError: x.map is not a function 今回やろうとしたこと inputタグを利用してファイルを複数選択できるようにし、そのファイル群をmapメソッドで処理するというもの。 ただ、今回のケースと違っていても同じ考え方で解決できる問題はあるはず。
既然你已经触及了dirtyUserData条目（我会注意到，在内部改变给定的参数通常是不好的），那么就复制到一...
testMap.get(function () {}) //undefined testMap.get(Symbol('Web')) //undefined //虽然NaN !== NaN 但是作为Map键名并无区别 testMap.get(NaN) //"我是个NaN" testMap.get(Number('NaN')) //"我是个NaN" 1. 2. 3. 4. 5.