js save files

//javascript
function download(text, name, type) {
  var a = document.getElementById("a");
  var file = new Blob([text], {type: type});
  a.href = URL.createObjectURL(file);
  a.download = name;
}
//html
<a href="" id="a">click here to download your file</a>
<button onclick="download('file text', 'myfilename.txt', 'text/plain')">Create file</button>