javascript - 在 ES6 中过滤和组合嵌套数组

Question

我需要合并 gid 和 subGroups 并将其输出到一个字符串数组中而不重复。我现在的问题是它只能获得第一级。

const oldGroup = [
    {
        "gid": "JFK",
        "subGroups": [
            "SFO",
            "LAX"
        ]
    },
    {
        "gid": "JFK",
        "subGroups": [
            "SFO",
            "LAX"
        ]
    },
    {
        "gid": "SFO",
        "subGroups": []
    },
    {
        "gid": "LAX",
        "subGroups": [
            "LGA"
        ]
    }
]

const newGroup = [...new Set(oldGroup.map((group) => group.gid))]

console.log(newGroup)

Answer 1

有几种方法可以实现这一点，这里是使用 .reduce() 的方法:

const oldGroup = [
    { "gid": "JFK", "subGroups": [ "SFO", "LAX" ] },
    { "gid": "JFK", "subGroups": [ "SFO", "LAX" ] },
    { "gid": "SFO", "subGroups": [] },
    { "gid": "LAX", "subGroups": [ "LGA" ] }
];

const newGroup = Object.keys(oldGroup.reduce((acc, obj) => {
  acc[obj.gid] = true;
  obj.subGroups.forEach(name => { acc[name] = true; } );
  return acc;
}, {}));

console.log(newGroup)

解释:

• .reduce() 有两个参数:
  • 一个函数参数有两个选项 acc, obj。前者是记录所需数据的累加器，后者是数组项对象
  • 一个初始设置，在我们的例子中是空的 {} 对象
• Object.keys() 应用于累积数据