数组中reduce的使用方法-蒲公英云

数组中reduce的使用方法

向右看齐 2022-11-30 04:12 317阅读 0赞

1.出现元素的次数:

<!DOCTYPE html>
<html>
<head>
    <title></title>
</head>
<body>
</body>
</html>
<script type="text/javascript">
    //出现元素的次数
function arrCount(arr,val){
   let count=arr.reduce((pre,cur,index)=>{
     console.log(pre,cur);
     return pre+=cur==val?1:0
   },0)
   return count
}
console.log(arrCount([1,5,3,4,8,1,1],1));//3
</script>

2.求数组最大值:

//求最大值
function arrCount(arr){
   let count=arr.reduce((pre,cur,index)=>{
     console.log(pre,cur);
     return pre>cur?pre:cur
   })
   return count
}
console.log(arrCount([1,5,3,4,8,1,1]));

3.数组去重使用reduce

<!DOCTYPE html>
<html>
<head>
    <title></title>
</head>
<body>
</body>
</html>
<script type="text/javascript">
    let goods=[
      {name:'apple',price:2000},
      {name:'huawei',price:1321},
      {name:'huawei',price:1421},
      {name:'huawei',price:13221},
      {name:'mi',price:20000},
      {name:'mi',price:20000},
    ]
    //数组去重
function filterGoods(arr){
   return arr.reduce((pre,cur)=>{
       //去找数组中是否有重复的数据有就返回true
     let bool=pre.find((val)=>{
           return val.name==cur.name
      })
     //没有这个值就追加进去
     if(!bool){
         pre.push(cur)
     }
     return pre
   },[])
}
console.log(filterGoods(goods))
</script>