How to make a file downloadable with only JavaScript

Google Chrome likes this. Others I don't know.

data:text/html,<a id="download">Down it goes</a>
<script type="text/javascript">
var a = document.getElementById('download');
var blob = new Blob(
  ["It is just a test, but I like it"], 
  { type: "text/plain" }
);
a.download = "love.txt";
a.href = window.URL.createObjectURL(blob);
</script>

Copy, paste in browser URL.