#appengine python
values = [1,2,3,4]
values = array('f',values)
response.out.write(values.tostring())

//JS loading
var xhr = new XMLHttpRequest();
xhr.open('GET', '/path/to/file', true);
xhr.responseType = 'arraybuffer';

xhr.onload = function(e) {
  var binaryArray = new Float32Array(this.response);
};
xhr.send();