<script type="text/javascript" data-cfasync="false">
function download(){
    var text = document.getElementById("my-textarea").value;
    text = text.replace(/\n/g, "\r\n"); // To retain the Line breaks.
    var blob = new Blob([text], { type: "text/plain"});
    var anchor = document.createElement("a");
    anchor.download = "percent.txt";
    anchor.href = window.URL.createObjectURL(blob);
    anchor.target ="_blank";
    anchor.style.display = "none"; // just to be safe!
    document.body.appendChild(anchor);
    anchor.click();
    document.body.removeChild(anchor);
 }
</script>

<textarea id="my-textarea" style="vertical-align: top; position:relative; display: inline-block; width:15%; min-height:200px; background:none;">
Notes here...
</textarea>
<button type="button" onclick="download()">Save</button>