包含对象数组和字符串数组的对象

Question

我有一个看起来像这样的对象：

var obj = {
  "array1": [
    {"label": "something1", "ref": "option2a"},
    {"label": "something2", "ref": "option2b"},
    {"label": "something3", "ref": "option2a"},
    {"label": "something4", "ref": "option2a"},
    {"label": "something5 is the longest", "ref": "option2a"}
  ],
  array2: [
    "arrayItem1",
    "array Item 2"
  ]
}

此对象包含对象数组和字符串数组。我想遍历每个具有标签的对象并返回最长的标签。在前面的示例中，预期的输出 id：

"something5 is the longest".

我尝试了以下方法：

function getLongest(object, key) {
  return Object.values(object).reduce((l, v) => {
    if (object.hasOwnProperty(key)) {
      if (key in v)
        return Math.max(l, v[key].length);
      if (v && typeof v === 'object')
        return Math.max(l, getLongest(v, key));
      return l;
    }
  }, 0);
}

但是这给了我一个错误，因为它找不到 label 的属性 array2 中的项目。

Answer 1

这里有一种方法，它使用了 reduce() 的动画方法，而不是 Object.Values()：

var obj = {
    "array1": [
        {"label": "something1", "ref": "option2a"},
        {"label": "something2", "ref": "option2b"},
        {"label": "something3", "ref": "option2ahgf"},
        {"label": "something4", "ref": "option2a"},
        {"label": "I'm not the longest", "ref": "option2a"}
    ],
    array2: [
        "arrayItem1",
        {"label": "something5 is the longest", "ref": "option2a"},
        "array Item 2"
    ],
    array3: [
        {"label": "somethingX", "ref": "option2X"},
        {"label": "somethingY", "ref": "option2Y"}
    ]
}

const getLongest = (obj, key) =>
{
    let r = Object.values(obj).reduce((res, curr) =>
    {
        if (!Array.isArray(curr))
            return res;

        let newMax = curr.reduce(
            (r, c) => c[[key]] && (c[[key]].length > r.length) ? c[[key]] : r,
            ""
        );

        res = newMax.length > res.length ? newMax : res;
        return res;

    }, "");

    return r;
}

console.log(getLongest(obj, "label"));
console.log(getLongest(obj, "ref"));

Answer 2

既然你提到了jQuery，我已经提供了一个解决方案，它使用jQuery.map 来迭代你的外部对象，并使用array.reduce 从obj 中的每个数组值中只产生一个结果。

var obj = {
  "array1": [{
      "label": "something1",
      "ref": "option2a"
    },
    {
      "label": "something2",
      "ref": "option2b"
    },
    {
      "label": "something3",
      "ref": "option2a"
    },
    {
      "label": "something4",
      "ref": "option2a"
    },
    {
      "label": "something5 is the longest",
      "ref": "option2a"
    }
  ],
  array2: [
    "arrayItem1",
    "array Item 2"
  ]
}
function getLongest(curr, next) {
  return !Object.keys(next).includes("label") || curr.label.length > next.label.length ? curr : next;
}

var reduced = $.map(obj, item => item.reduce(getLongest, {"label": ""}))
console.log(reduced);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

这基本上会遍历obj 中的每个键的值，并将数组缩减为具有最长label 标签的单个对象，如果它甚至有label 键的话。如果没有，它会返回一个没有标签的默认对象，并使用具有混合对象/字符串的数组。

所以它返回一个匹配键为obj的对象。

Answer 3

示例：

// object declaration
var obj = {
  "array1": [{
      "label": "something1",
      "ref": "option2a"
    },
    {
      "label": "something2",
      "ref": "option2b"
    },
    {
      "label": "something3",
      "ref": "option2a"
    },
    {
      "label": "something4",
      "ref": "option2a"
    },
    {
      "label": "something5 is the longest",
      "ref": "option2a"
    }
  ],
  array2: [
    "arrayItem1",
    "array Item 2"
  ]
};

// iterate over all items in obj
for (var propertyName in obj) {
  // if the item is an object and is an array
  if (typeof obj[propertyName] === 'object' && Array.isArray(obj[propertyName])) {
    // if the array has at least one item and a property of label
    if (obj[propertyName].length > 0 && typeof obj[propertyName][0].label !== 'undefined') {
      // sort the array by length of label
      obj[propertyName].sort((a,b) => (a.label.length < b.label.length) ? 1 : ((b.label.length < a.label.length) ? -1 : 0));
      // console.log print the longest label
      console.log('longest label name:', obj[propertyName][0].label);
    }
  }
}

// output the whole obj
console.log(obj);