Replace string in HTML

Target whole page – NOT RECOMDNDED
window.addEventListener('load', function()
{
  document.body.innerHTML = document.body.innerHTML.replaceAll(
    "REPLACE_THIS_TAG",
    "Replace with this"
  );
});

WARNING!!!!!! – This rewrites the entire <body>, the browser destroys the old DOM nodes and creates new ones. If you’ve already done things that like attach click handlers they won’t work!

Target a section of the page only – BETTER APPRAOCH

Better approach, target just a specific section of the page, e.g. within a specific <div> ID:

window.addEventListener('load', function()
{
  const MyContainerId = document.getElementById('MyContainerId');
  if(MyContainerId)
  {
    MyContainerId.innerHTML = MyContainerId.innerHTML.replaceAll(
      "REPLACE_THIS_TAG",
      "Replace with this"
    );
  }
});