getelementbyid

1var element = document.getElementById("YourElementId");

1document.getElementById("someid");

1<h1 id="demo">
2
3<style>function demoFunction()
4{document.getElementById("demo"). //Add what you want to change right here.}
5</style>

1document.getElementById("YourElementId");

1document.getElementById("some_id");

1var myElement=document.getElementById("someElementID");