Question

我有一个像这样的对象数组：

[ {"name": "apple", "id": "apple_0"}, 
  {"name": "dog",   "id": "dog_1"}, 
  {"name": "cat", "id": "cat_2"}
]

我想插入另一个名为apple的元素，但是，因为我不想在那里复制，我怎么能用lodash来查看数组中是否有一个对象一样的名字？

Answer 1

您可以像这样使用Lodash _.find()。

var data = [ {"name": "apple", "id": "apple_0"}, 
  {"name": "dog",   "id": "dog_1"}, 
  {"name": "cat", "id": "cat_2"}
]

if(!_.find(data, {name: 'apple'})) {
  data.push({name: 'apple2'});
}
console.log(data)

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

Answer 2

这是表格

_.has(object, path)

示例：

const countries = { country: { name: 'Venezuela' } }
const isExist = _.has(countries, 'country.name')
// isExist = true

了解更多信息Document Lodash

Answer 3

您可以使用Array.prototype.find()或lodash＆＃39; _.find()：

＆＃13;

const addItem = (arr, item) => {
  if(!arr.find((x) => x.name === item.name)) { // you can also change `name` to `id`
    arr.push(item);
  }
};

const arr = [ 
  {"name": "apple", "id": "apple_0"}, 
  {"name": "dog",   "id": "dog_1"}, 
  {"name": "cat", "id": "cat_2"}
];

addItem(arr, { "name": "apple", "id": "apple_0" });

addItem(arr, { "name": "pear", "id": "pear_3" });

console.log(arr);

＆＃13;

有点短但可读性较差的版本：

＆＃13;

    const addItem = (arr, item) => arr.find((x) => x.name === item.name) || arr.push(item); // you can also change `name` to `id`

    const arr = [ 
      {"name": "apple", "id": "apple_0"}, 
      {"name": "dog",   "id": "dog_1"}, 
      {"name": "cat", "id": "cat_2"}
    ];

    addItem(arr, { "name": "apple", "id": "apple_0" });

    addItem(arr, { "name": "pear", "id": "pear_3" });

    console.log(arr);

＆＃13;

Answer 4

这是lodash的另一个例子

var a = [ {"name": "apple", "id": "apple_0"}, 
  {"name": "dog",   "id": "dog_1"}, 
  {"name": "cat", "id": "cat_2"}
]

var b = _.find(a, ['name', "apple2"]);

if(_.isObject(b)){
  console.log('exists')
}else{
    console.log('insert new')
}

https://jsfiddle.net/jorge182/s4og07jg/

Answer 5

这对我有用（在测试不同的解决方案后）：

  addItem(items, item) {
    let foundObject = _.find(items, function(e) {
      return e.value === item.value;
    });

    if(!foundObject) {
      items.push(item);
    }
    return items;
  }

Answer 6

以下是使用lodash 4.17.5实现此目的的三种方法：

假设您想要将对象entry添加到对象数组numbers，只有当entry不存在时才会这样。

let numbers = [
    { to: 1, from: 2 },
    { to: 3, from: 4 },
    { to: 5, from: 6 },
    { to: 7, from: 8 },
    { to: 1, from: 2 } // intentionally added duplicate
];

let entry = { to: 1, from: 2 };

/* 
 * 1. This will return the *index of the first* element that matches:
 */
_.findIndex(numbers, (o) => { return _.isMatch(o, entry) });
// output: 0


/* 
 * 2. This will return the entry that matches. Even if the entry exists
 *    multiple time, it is only returned once.
 */
_.find(numbers, (o) => { return _.isMatch(o, entry) });
// output: {to: 1, from: 2}


/* 
 * 3. This will return an array of objects containing all the matches.
 *    If an entry exists multiple times, if is returned multiple times.
 */
_.filter(numbers, _.matches(entry));
// output: [{to: 1, from: 2}, {to: 1, from: 2}]


/* 
 * 4. This will return `true` if the entry exists, false otherwise.
 */
_.some(numbers, entry);
// output: true

如果要返回Boolean（即，假设您没有使用_.some()），在第一种情况下，您只需检查正在返回的索引值：

_.findIndex(numbers, (o) => { return _.isMatch(o, entry) }) > -1;
// output: true

Lodash documentation是示例和实验的重要来源。

Answer 7

如果您只想在数组中插入一个值，那么使用_.find可能是一个选项。但是，如果您有兴趣插入一个或多个，我建议改为使用_.unionBy：

var currentArr = [{
    "name": "apple",
    "id": "apple_0"
  }, {
    "name": "dog",
    "id": "dog_1"
  }, {
    "name": "cat",
    "id": "cat_2"
  }],
  arrayOneValue = [{
    "name": "apple",
    "id": "apple_0"
  }],
  arrayTwoValues = arrayOneValue.concat({
    "name": "lemon",
    "id": "lemon_0"
  })

console.log(_.unionBy(currentArr, arrayOneValue, 'name'));
console.log(_.unionBy(currentArr, arrayTwoValues, 'name'));
// It also allow you to perform the union using more than one property
console.log(_.unionBy(currentArr, arrayTwoValues, 'name', 'id'));

<script src="https://cdn.jsdelivr.net/lodash/4.16.4/lodash.min.js"></script>

Lodash查找对象属性是否存在于数组中

7 个答案: