如何根据属性值过滤数组并返回对象数组

Question

我有这个带有name和isPinned键的对象数组。 我只想根据isPinned将国家/地区名称存储在一个新数组中。 例如，如果澳大利亚和中国将isPinned设为 true，那么新数组将是：

const countriesFiltered = ["Australia", "China"]

const countries = [
    { name: "Australia", isPinned: true },
    { name: "China", isPinned: true },
    { name: "India", isPinned: false },
  ];

Answer 1

你会.filter按isPinned然后按name .map

const namesOfPinnedCountries = countries
    .filter(it => it.isPinned)
    .map(it => it.name)

Answer 2

.filter()和.map()是经典的解决方案，但您也可以使用.reduce()来实现：

 const countries = [ { name: "Australia", isPinned: true }, { name: "China", isPinned: true }, { name: "India", isPinned: false }, ]; const res=countries.reduce((a,c)=> c.isPinned?[...a,c.name]:a,[]); console.log(res);

Answer 3

您可以使用flatMap ：

 const countries = [ { name: "Australia", isPinned: true }, { name: "China", isPinned: true }, { name: "India", isPinned: false }, ]; const countriesFiltered = countries.flatMap(i => i.isPinned? i.name: []); console.log(countriesFiltered);