    <ul><li>Hello</li></ul>
    <div class="output">
        <h1>Hello</h1>
        <div>Test</div>
        <ul>
            <li id="one">One</li>
            <li class="red">Two</li>
        </ul>
        <div>Test</div>
    </div>

    <script>
        const output = document.querySelector(".output");
        const mainList = output.querySelector("ul");
        mainList.id = "mainList";
        console.log(mainList)
        const eles = output.children;
        for(let x=0;x<eles.length;x++){
            console.log(eles[x].tagName);
            eles[x].id = "id"+(x+1);
            if(x%2){
                eles[x].style.color = "red";
            }
        }

    </script>
