每个循环嵌套的重构

Question

下面的代码可以迭代来自对象的贴纸信息。为此，我对每个都使用两个嵌套的。在提交中是否有更好的方法来重构下面的代码而不使用嵌套的forEach或任何更好的建议。

var stickers = [];
_.forEach(data.families.categories, function (category) {
    _.forEach(category.stickers, function (sticker) {
        stickers.push(sticker);
    });
});

下面是对象示例

var data = {
  "families": {
    "id": "my_family",
    "categories": [
      {
        "label": "sample-1",
        "id": "family-0",
        "stickers": [
          "aa",
          "bb",
          "cc"
        ]
      },
      {
        "label": "US",
        "id": "family-1",
        "stickers": [
          "DD",
          "EE"
        ]
      },
      {
        "label": "sample-2",
        "id": "family-2",
        "stickers": [

        ]
      },
      {
        "label": "sample-3",
        "id": "family-3",
        "stickers": [
          "FF",
          "GG",
          "HH",
          "II",
          "JJ"
        ]
      }
    ]
  }
}

Answer 1

Lodash提供了flatMap函数，它可以做您想做的事情：

var stickers =_.flatMap(data.families.categories, 'stickers');

​

	var data = {
  "families": {
    "id": "my_family",
    "categories": [
      {
        "label": "sample-1",
        "id": "family-0",
        "stickers": [
          "aa",
          "bb",
          "cc"
        ]
      },
      {
        "label": "US",
        "id": "family-1",
        "stickers": [
          "DD",
          "EE"
        ]
      },
      {
        "label": "sample-2",
        "id": "family-2",
        "stickers": [

        ]
      },
      {
        "label": "sample-3",
        "id": "family-3",
        "stickers": [
          "FF",
          "GG",
          "HH",
          "II",
          "JJ"
        ]
      }
    ]
  }
}
    
    var stickers =_.flatMap( data.families.categories, 'stickers');

document.getElementById('result').textContent = JSON.stringify(stickers);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>

<p>
  <pre id="result"></pre>
</p>

​

Answer 2

您可以结合使用Array#reduce和Array#concat。

​

var data = { "families": { "id": "my_family", "categories": [{ "label": "sample-1", "id": "family-0", "stickers": ["aa", "bb", "cc"] }, { "label": "US", "id": "family-1", "stickers": ["DD", "EE"] }, { "label": "sample-2", "id": "family-2", "stickers": [] }, { "label": "sample-3", "id": "family-3", "stickers": ["FF", "GG", "HH", "II", "JJ"] }] } },
    stickers = data.families.categories.reduce(function (r, category) {
        return r.concat(category.stickers);
    }, []);

console.log(stickers);

​