Lodash过滤器从数组（Vue）中搜索少量元素

Question

I have an object:

{
   1: {
         name: 'Adam',
         age: 12,
      },
   2: {
         name: 'Michal',
         age: 14,
      },
   3: {
         name: 'Jozef',
         age: 12,
      }
}

I tried using function filter from lodash:

this.knowledges = _.filter(this.knowledges, function (item) {
    if (item.category[1] !== undefined) {
        return arrayOfNumbers.indexOf(item.category[1].category_id) >= 0
    }
})

Variable arrayOfNumbers return array: [1,3] so function filter should return:

{
   1: {
         name: 'Adam',
         age: 12,
      },
   3: {
         name: 'Jozef',
         age: 12,
      }
}

But it returns only first index:

{
   1: {
         name: 'Adam',
         age: 12,
      }
}

How can I fix it ?

Answer 1

You could use pickBy like this:

 const knowledges = {1:{name:"Adam",age:12,},2:{name:"Michal",age:14,},3:{name:"Jozef",age:12,}}, arrayOfNumbers = [1,3], result = _.pickBy(knowledges, (v, k) => arrayOfNumbers.includes(+k)); console.log(result) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script> 

In vanilla JS, you could filter the the entries of the object and create an object using Object.fromEntires() like this:

 const knowledges={1:{name:"Adam",age:12,},2:{name:"Michal",age:14,},3:{name:"Jozef",age:12,}}, arrayOfNumbers=[1,3]; const newObject = Object.fromEntries( Object.entries(knowledges).filter(([k, v]) => arrayOfNumbers.includes(+k)) ) console.log(newObject) 

Answer 2

With lodash you can use _.pick() . Pick takes an object, and an array of properties, and generates a new object with the selected properties:

 const knowledges = {1:{name:"Adam",age:12,},2:{name:"Michal",age:14,},3:{name:"Jozef",age:12,}} const arrayOfNumbers = [1,3] const result = _.pick(knowledges, arrayOfNumbers) console.log(result) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script> 

The _.pickBy() method works identically to filter for objects, so you can query the objects values, when you decide what to keep.

In this examples, I use _.pickBy() to keep all items with age === 12 :

 const knowledges = {1:{name:"Adam",age:12,},2:{name:"Michal",age:14,},3:{name:"Jozef",age:12,}} const result = _.pickBy(knowledges, o => o.age === 12) console.log(result) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>