Instead of calling the function UpdatePoints() in window.onload, you need to wrap the call in a function that gets assigned by reference to window.onload. Otherwise, you are calling the function, and assigning its return value to window.onload.

// This function wraps UpdatePoints($test)

// and is assigned as a reference to window.onload

function load() {

  UpdatePoints(<?php echo $test; ?>);

}

echo <script type='text/javascript'> window.onload=load; </script>;

Note that the language attribute to the <script> tag is deprecated. Include a type=text/javascript attribute in its place (though text/javascript is genearlly the browser default)

However, since the value of $test is created before the page loads and cannot change when the function is called, you might as well not bother passing it as a parameter, in which case you don't need to wrap the function. Just remove the () to assign it as a reference.

echo <script type='text/javascript'> window.onload=UpdatePoints; </script>;



function UpdatePoints() {

  // PHP write directly into the function since the value

  // can't change...  It's always going to be passed as what PHP assigns 

  // if you call it as UpdatePoints($test)

  var Points = $test;

  document.getElementById('PointsNumber').innerHTML = Points;

}