从Map.values（）中选择一个属性

Question

我想要这样的东西：

let myMap = new Map<string, any>();

myMap.set("aaa", {a: 1, b: 2, c:3});
myMap.set("bbb", {a: 1, b: 2, c:6});
myMap.set("ccc", {a: 1, b: 2, c:9});

let cs = myMap.values().map(x => x.c);

从地图的所有条目中选择c属性。这是失败的：

Property 'map' does not exist on type 'IterableIterator<any>'.

对此有什么优雅的解决方案？

Answer 1

您可以使用Array.from()将所有可迭代对象转换为数组：

let myMap = new Map();

myMap.set("aaa", {a: 1, b: 2, c:3});
myMap.set("bbb", {a: 1, b: 2, c:6});
myMap.set("ccc", {a: 1, b: 2, c:9});

// Basic example
let cs = Array.from( myMap.values() ).map(x => x.c);

console.log( cs );

// Array.from also takes a mapping function as the second parameter, so even shorter:

let cs_alt = Array.from( myMap.values(), x => x.c );

console.log( cs_alt );