dynamic itemprop URL for Schema Mircodata

[BadCoder]

This is my first post and I'm not very good with Java. I'm trying to automatically create the following schema meta tag for my website:

<meta itemprop="url" content="URLofthispage" />

The best I came up (pieced together from the internet) with is:

<script>var addLink = function(url){
  var link = document.createElement('meta');
  link.setAttribute('itemprop', 'url');
  link.content =  window.location.href;
  document.getElementsByID('placehere')[0].appendChild(link);
</script>

And then <p id="placehere"><p> to place the meta tag in the correct location in my code.

I have tried the same format also for <link itemprop="url" href="URLofthispage" /> which can also be used for the url tag.

Any suggestions would be greatly appreciated.