两个数组找相同的值

 let arr1 =[1,2,3]  //跟
 let arr2 =[4,6,5]  //子
 let arr3 =[1,2,6]  //根子都有
 let frist =arr3.filter(item=> arr1.indexOf(item)>-1) //跟
 let frist1 =arr3.filter(item=> arr2.indexOf(item)>-1)//子
 console.log(frist)
 console.log(frist1)