PHP code for innerHTML

I have a php page with a loop that gets some data from a DOMDocument using getElementById. At a point in the php loop, I need to insert the a value into a elementById on the same php page. I need either some php code to insert into innerHTML, or a way to call a javascript code to insert into the innerHTML. I have a javascript that works when the user clicks a button. Maybe it is possible for the php code to "click" the button which will call the javascript? If possible to click the button, then I only need to do that once. Otherwise, during each php, the php code gets a variable/value. Each value needs to get inserted into an element then the php loop continues.