Lodash：切片数组并保留特定项目

Question

我有一个从 API 获得的对象数组，其中 1 个对象具有“选定”属性。我需要将该数组切片为只有 3 个对象，并且其中 1 个对象需要是“选定”对象。我在角度应用程序中使用 lodash，但我不限于如何实现这一点，尽管我更喜欢使用 lodash 的答案。在此先感谢...请参见下面的示例：

//Sample array
var fruits = [{
  id: 1,
  fruit: "apple",
  selected: false
}, {
  id: 2,
  fruit: "pear",
  selected: false
}, {
  id: 3,
  fruit: "orange",
  selected: false
}, {
  id: 4,
  fruit: "pineaple",
  selected: false
}, {
  id: 5,
  fruit: "mango",
  selected: true
}, {
  id: 6,
  fruit: "peach",
  selected: false
}, {
  id: 7,
  fruit: "strawberry",
  selected: false
}];

预期结果：

var fruits = [{
  id: 1,
  fruit: "apple",
  selected: false
}, {
  id: 2,
  fruit: "pear",
  selected: false
}, {
  id: 5,
  fruit: "mango",
  selected: true
}];

Answer 1

在这里做出 3 个假设，但是：

var sliced = fruits.slice(0,3);

for (var i=3; i<fruits.length; i+=1)
    if (fruits[i].selected)
        sliced[0] = fruits[i];

Answer 2

从不理解 IE8 后下划线或 lodash 的吸引力。现代 JS 中提供了大量出色的便捷方法。更多关于原生 JS 数组方法的信息：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array

    //Sample array
    var fruits = [{
      fruit: "apple",
      selected: false
    }, {
      fruit: "pear",
      selected: false
    }, {
      fruit: "orange",
      selected: false
    }, {
      fruit: "pineaple",
      selected: false
    }, {
      fruit: "mango",
      selected: true
    }, {
      fruit: "peach",
      selected: false
    }, {
      fruit: "strawberry",
      selected: false
    }];

function fruitCheck(obj){
    var isDesiredFruit = (obj.fruit === 'mango') ||
        (obj.fruit === 'peach') ||
        (obj.fruit === 'strawberry');
    return isDesiredFruit;
}

var filteredFruits = fruits.filter(fruitCheck);

Answer 3

试一试：

function getThreeFruits (fruits) {
  var split = _.partition(fruits, { selected: true })
  var selectedFruit = split[0]
  var twoOtherFruits = split[1].slice(0, 2)
  return selectedFruit.concat(twoOtherFruits)
}

Answer 4

有很多方法可以解决这个问题！这是另一个 Vanilla Javascript 版本，可根据您的实际规格随意混合和匹配。

var fruits = [{
  fruit: "apple",
  selected: false
}, {
  fruit: "pear",
  selected: false
}, {
  fruit: "orange",
  selected: false
}, {
  fruit: "pineaple",
  selected: false
}, {
  fruit: "mango",
  selected: true
}, {
  fruit: "peach",
  selected: false
}, {
  fruit: "strawberry",
  selected: false
}];

var selectedFruits = fruits.reduce((result, el) => {
  if(el.selected) {
    return Array(el).concat(result).slice(0, 3);
  }
  if (result.length > 2) return result;
  result.push(el);
  return result;
}, Array());

console.log(selectedFruits);

Answer 5

var z= _.sortBy(fruits,function(obj){return obj.selected})
var result.push(z.slice(0,2));
result.push(z[z.length-1]);

Answer 6

在查看了所有答案后，我决定使用这样的东西。

return user.userStoreAccesses
  .reduce(function(arr, el) {
    //check if current obj is the defaultStore
    if (el.defaultStore) {
      return [el].concat(arr).slice(0, 3);
    }
    //the moment the array is greater than 2 stop execution
    if (arr.length > 2) {
      return arr;
    }
    //keep pushing items to the array until...
    arr.push(el);
    return arr;
  }, []);

但是，我决定通过链接一些 lodash 方法（这是我的初衷）更简单一些。这是最终结果：

return _(user.userStoreAccesses)
  .chain()
  .sortBy("defaultStore")
  .reverse()
  .slice(0, 3)
  .value();

感谢您的回答，他们非常有帮助！ 我希望我的方法对其他人也有用:)