how to make a download js code example

Example 1: javascript write to file and download

function download(filename, text) {
  var element = document.createElement('a');
  element.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text));
  element.setAttribute('download', filename);

  element.style.display = 'none';
  document.body.appendChild(element);

  element.click();

  document.body.removeChild(element);
}

// Start file download.
download("hello.txt","This is the content of my file :)");

Example 2: javascript download file

$('a#someID').attr({target: '_blank', 
                    href  : 'http://localhost/directory/file.pdf'});