Creating a downloadable text-file using blobs

Created as part of my answer to http://stackoverflow.com/questions/8178825/create-text-file-in-javascript

HTML

<textarea id="textbox">Type something here</textarea> <button id="create" onclick="call()">Create file</button> <a download="info.txt" id="downloadlink" style="display: none">Download</a>

JavaScript

alert('test');

  function makeTextFile(text) {
   var textFile = null;
   var data = new Blob([text], {type: 'text/plain'});

    // If we are replacing a previously generated file we need to
    // manually revoke the object URL to avoid memory leaks.
    if (textFile !== null) {
      window.URL.revokeObjectURL(textFile);
    }

    textFile = window.URL.createObjectURL(data);

    return textFile;
  };


  
   
   function call(){
   var create = document.getElementById('create');
    var textbox = document.getElementById('textbox');
    var link = document.getElementById('downloadlink');
    link.href = makeTextFile(textbox.value);
    link.style.display = 'block';
  };