如何在React Native中过滤数组？

Question

我有数组

 const arr = [
    {id: 1, country: 'Austria'},
    {id: 2, country: 'Germany'},
    {id: 3, country: 'Austria'},
  ];

我尝试了以下代码来过滤它。

arry.map((item,idx) => (
   item.country== "Austria"?(
       console.log(item.id)
   )
   :
   null
))

输出是

1 3

, 但我想在整个过滤器之后获得输出，例如

1,3

我只想要国家为奥地利的 ID，如下所示。

1,3

Answer 1

使用

reduce

功能

const arry = [
    {id: 1, country: 'Austria'},
    {id: 2, country: 'Germany'},
    {id: 3, country: 'Austria'},
  ];
  
   const result = arry.reduce((acc,item,idx) => {
    
          if(item.country == "Austria"){
             if(idx === 0) acc += item.id
             else acc += `,${item.id}`
           }
           
           return acc
      
    }, '')
    
    console.log(result)

Answer 2

这就是我的过滤方式

const arry = [
    {id: 1, country: 'Austria'},
    {id: 2, country: 'Germany'},
    {id: 3, country: 'Austria'},
];

const result = arry.filter((item, index) => {

      if(item.country == "Austria"){
         return true
       }
       
       else{
        return false
       }
  
})

console.log(result)

Answer 3

一行答案：

arr.filter(i => i.country == 'Austria')

Answer 4

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