从 Javascript 数组对象中提取字段名称

Question

我想从数组对象中提取字段名称，称为

results

，在 Javascript 中具有以下结构

    Object { data: (5) […] }
    ​
     data: Array(5) [ {…}, {…}, {…}, … ]
    ​​
      0: Object { nClients: 4 }
    ​​
      1: Object { name: "test1", roll_no: 321, branch: "it" }
    ​​
      2: Object { name: "test2", roll_no: 321, branch: "it" }
    ​​
      3: Object { name: "test3", roll_no: 321, branch: "it" }
    ​​
      4: Object { name: "test4", roll_no: 321, branch: "it", … }
    
      length: 5
    ​​
     <prototype>: Array []

​
<prototype>: Object { … }

我想提取一个字段列表，例如

[nClients, name, roll_no, branch]

。有什么建议吗？ 谢谢！

Answer 1

您可以使用

Array#reduce

和

Object.keys()

来收集集合中的道具名称：

const arr = [
 { nClients: 4 },
 { name: "test1", roll_no: 321, branch: "it" },
 { name: "test2", roll_no: 321, branch: "it" },
 { name: "test3", roll_no: 321, branch: "it" },
 { name: "test4", roll_no: 321, branch: "it" , prop1: true},
];

const fields = [...arr.reduce((r, i) => (Object.keys(i).forEach(k => r.add(k)), r), new Set)];

console.log(...fields);