JS

    <script>let arr=[1,2,3,4,5,4,3,2,1];//1.数组去重let result0=[...new Set(arr)];console.log(`数组去重${result0}`);//2.交集let arr2=[4,5,6,5,6];let result=[...new Set(arr)].filter(item=>{let s2=new Set(arr2);//4 5 6if(s2.has(item)){return true;}else{return false;}})console.log(`交集${result}`);let result2=[...new Set(arr)].filter(item=>new Set(arr2).has(item));console.log(`交集${result2}`);//3.并集let union=[...new Set([...arr,...arr2])];console.log(`并集${union}`);//4.差集let diff=[...new Set(arr)].filter(item=> !(new Set(arr2).has(item)));console.log(`并集${diff}`);</script>