Question

For instance in the snippet below – how do I access the h1 element knowing the ID of parent element (header-inner div)?

<div id='header-inner'>     <div class='titlewrapper'>        <h1 class='title'>        Some text I want to change       </h1>     </div>  </div> 

Thanks!

Answer 1

function findFirstDescendant(parent, tagname) {    parent = document.getElementById(parent);    var descendants = parent.getElementsByTagName(tagname);    if ( descendants.length )       return descendants[0];    return null; }  var header = findFirstDescendant('header-inner', 'h1'); 

Finds the element with the given ID, queries for descendants with a given tag name, returns the first one. You could also loop on descendants to filter by other criteria; if you start heading in that direction, i recommend you check out a pre-built library such as jQuery (will save you a good deal of time writing this stuff, it gets somewhat tricky).