SOURCE

let arr = [1,2,3,7,8,9,10]
        function setArr(item){
            let s1 = new Set([...arr,...item]);
            let arr2 = [];
            for(let a of s1){
                 arr2.push(a);
            }

            return arr2.filter(e=>item.includes(e))
        }
        console.log(setArr([1,3,4,5]))
        console.log(setArr([1,2,3,4,11]))

let arr1 = [1,2,3,7,8,9,10]

    function setArr1(item){
        let newArr = []
        for(let i=0;i<item.length;i++){
            let isa = true
            for(let j=0;j<arr1.length;j++){
                if(item[i]==arr1[j]){
                    newArr.push(arr1[j])
                    isa = false
                }
            }
            if(isa) newArr.push(item[i])
            
        }
        return newArr
    }

    console.log(setArr1([1,3,4,5]))
    console.log(setArr1([1,2,3,4,11]))