javascript 对象从键数组中获取值数组

Question

我有一个键数组：var keys = ["key1","key2","key3"] 和一个对象数组：

var objArr= [
    {"key0":1,"key1":2,"key2":3,"key3":4},
    {"key0":5,"key1":6,"key2":7,"key3":8}
]

我希望能够根据键数组从对象数组中获取值。例如，此输出将是 valueArr = [[2,3,4],[6,7,8]]

我试过以下方法：

var result = objArr.map(function(a) {
    for (var i=0;i<keys.length;i++){
        return a[keys[i]];
    };
})

但是这个 returns [2,6] 因为它只是返回它到达的第一个值。我不确定如何修复它，所以感谢您的帮助，谢谢！

Answer 1

不要return太早，循环只经过第一项:

var result = objArr.map(function(a) {
    var resp = [];
    for (var i=0;i<keys.length;i++){
        resp.push(a[keys[i]]);            
    };
    return resp;
})

Answer 2

将 value 推入数组并从 Array#map

推入 return array

var keys = ["key1", "key2", "key3"];
var objArr = [{
  "key0": 1,
  "key1": 2,
  "key2": 3,
  "key3": 4
}, {
  "key0": 5,
  "key1": 6,
  "key2": 7,
  "key3": 8
}];

var result = objArr.map(function(a) {
  var arr = [];
  for (var i = 0; i < keys.length; i++) {
    arr.push(a[keys[i]]);
  };
  return arr;
});
console.log(result);

或在 Array#map

中使用 Array#map

var keys = ["key1", "key2", "key3"];
var objArr = [{
  "key0": 1,
  "key1": 2,
  "key2": 3,
  "key3": 4
}, {
  "key0": 5,
  "key1": 6,
  "key2": 7,
  "key3": 8
}];

var result = objArr.map(function(a) {
  return keys.map(function(key) {
    return a[key];
  });
});
console.log(result);

Answer 3

您需要将值压入数组，return 将立即中断执行并 return 值。

试试这个：

var result = objArr.map(function(a) {
    var res = [];
    for (var i=0;i<keys.length;i++){
        res.push(a[keys[i]]);
    };
    return res;
})

Answer 4

作为 替代方案，您可以使用 Object.values() 函数，如 here 所建议。示例：

var objArr= [
    {"key0":1,"key1":2,"key2":3,"key3":4},
    {"key0":5,"key1":6,"key2":7,"key3":8}
];

for(var i in objArr){
    objArr[i] = Object.values(objArr[i]);
}

目前 Internet Explorer、Opera 或 Safari 不支持此功能

Answer 5

您可以使用嵌套 Array#map。

var keys = ["key1", "key2", "key3"],
    objArr = [{ "key0": 1, "key1": 2, "key2": 3, "key3": 4 }, { "key0": 5, "key1": 6, "key2": 7, "key3": 8 }],
    result = objArr.map(function (a) {
        return keys.map(function (k) {
            return a[k];
        });
    });

console.log(result);

ES6

var keys = ["key1", "key2", "key3"],
    objArr = [{ "key0": 1, "key1": 2, "key2": 3, "key3": 4 }, { "key0": 5, "key1": 6, "key2": 7, "key3": 8 }],
    result = objArr.map(a => keys.map(k => a[k]));

console.log(result);

javascript 对象从键数组中获取值数组

javascript object get array of values from array of keys

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