JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="audiocontent"></textarea>

<input type="button" value="to wav" id="save"/>

JavaScript

var box = document.getElementById("audiocontent")
var btn = document.getElementById("save")


function doSave() {
  var snd = new Audio("data:audio/wav;base64," + box.value);
  snd.play()
  var link = document.createElement("a");
  link.name = "audio.wav"
  link.download = "audio.wav";
  link.href = snd.src;
  link.click()
}

btn.addEventListener("click", doSave)