javascript - 在每次地图迭代的开头添加对象

Question

所以，让我们假设我有这个：

var officers = [
  { id: 20, name: 'Captain', lastName: 'Piett' },
  { id: 24, name: 'General', lastName: 'Veers'  },
  { id: 56, name: 'Admiral', lastName: 'Ozzel'  },
  { id: 88, name: 'Commander', lastName: 'Jerjerrod'  }
];

如果我这样做： var officersIds = officers.map(x => [x.name, x.lastName]); 结果officersIds是会是这样的：

[ "Captain", "Piett" ], [ "General", "Veers" ], [ "Admiral", "Ozzel" ], [ "Commander", "Jerjerrod" ]

对？

所以，我需要做的是在每次地图迭代上放置一个对象，因此输出现在是这样的，例如：

[["x", "y"], [ "Captain", "Piett" ]], 
[["x", "y"], [ "General", "Veers" ]],  
[["x", "y"], [ "Admiral", "Ozzel" ]], 
[["x", "y"], [ "Commander", "Jerjerrod" ]]

为什么我需要这个？ 最好不要问;) 但这是一个复杂的问题，如果你帮我解决这个简单的问题，我可以将你的解决方案转移到我的复杂问题上。

重要提示：有没有办法在一行中做到这一点？

Answer 1

var officers = [
  { id: 20, name: 'Captain', lastName: 'Piett' },
  { id: 24, name: 'General', lastName: 'Veers'  },
  { id: 56, name: 'Admiral', lastName: 'Ozzel'  },
  { id: 88, name: 'Commander', lastName: 'Jerjerrod' },
];

officers.unshift({ name: x, lastName: y });

var officersIds = officers.map(x => [x.name, x.lastName]);

或者

var officers = [
      { id: 20, name: 'Captain', lastName: 'Piett' },
      { id: 24, name: 'General', lastName: 'Veers'  },
      { id: 56, name: 'Admiral', lastName: 'Ozzel'  },
      { id: 88, name: 'Commander', lastName: 'Jerjerrod' },
    ];


    var officersIds = officers.map(x => [x.name, x.lastName]);

    officersIds.unshift(["x", "y" ]);

Answer 2

用地图过officers 。

 var officers = [ { id: 20, name: 'Captain', lastName: 'Piett' }, { id: 24, name: 'General', lastName: 'Veers' }, { id: 56, name: 'Admiral', lastName: 'Ozzel' }, { id: 88, name: 'Commander', lastName: 'Jerjerrod' } ]; var officersIds = officers.map(x => [["x", "y"], [x.name, x.lastName]]); console.log(officersIds);

Answer 3

如果您只想将['x', 'y']到数组的开头，您可以使用扩展运算符使其成为单行：

var officersIds = [['x', 'y'], ...officers.map(x => [x.name, x.lastName])];

请参阅下面的概念验证：

 var officers = [ { id: 20, name: 'Captain', lastName: 'Piett' }, { id: 24, name: 'General', lastName: 'Veers' }, { id: 56, name: 'Admiral', lastName: 'Ozzel' }, { id: 88, name: 'Commander', lastName: 'Jerjerrod' } ]; var officersIds = [['x', 'y'], ...officers.map(x => [x.name, x.lastName])]; console.log(officersIds);

---

但是，如果您想将['x', 'y']到数组中的每个项目，那么您应该这样做：

var officersIds = officers.map(x => [['x', 'y'], [x.name, x.lastName]]);

 var officers = [ { id: 20, name: 'Captain', lastName: 'Piett' }, { id: 24, name: 'General', lastName: 'Veers' }, { id: 56, name: 'Admiral', lastName: 'Ozzel' }, { id: 88, name: 'Commander', lastName: 'Jerjerrod' } ]; var officersIds = officers.map(x => [['x', 'y'], [x.name, x.lastName]]); console.log(officersIds);

Answer 4

您可以将所需的部分添加到映射函数中。

 var officers = [{ id: 20, name: 'Captain', lastName: 'Piett' }, { id: 24, name: 'General', lastName: 'Veers' }, { id: 56, name: 'Admiral', lastName: 'Ozzel' }, { id: 88, name: 'Commander', lastName: 'Jerjerrod' }], officersIds = officers.map(x => [["x", "y"], [x.name, x.lastName]]); console.log(officersIds);