gistfile1.txt

var email = 'abc@cde.frg'
var xhr = new XMLHttpRequest
xhr.onreadystatechange = function() {
  if (xhr.readyState == 4) {
    try {
      var response = JSON.parse(xhr.response);
    } catch (e) {
      var response = {
        status: xhr.status,
        title: xhr.response
      };
    }
    if (response.status != 400) {
      console.log(response)
    } else {
      console.error(response, response.errors, response.status, response.title)
    }
  }
}
xhr.open('POST', '//www.narrowdesign.com/scripts/mailchimp.php')
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); 
xhr.send('email=' + email)