javascript - Display result of js calculation in span -

i'm trying calculate in javascript , display result in <span></span>. code i've got @ moment:

<script type="text/javascript">  window.onload = function() {  function minus_number() {         var first_number = '50';         var second_number = '30';         var result = parseint(first_number) - parseint(second_number);          document.getelementbyid('spend').value = result;     } } 

and html

<p><i class="fa fa-truck"></i>want free delivery? spend <span id="spend"></span> free standard delivery</p> 

it doesn't display result in span though, can tell me i'm doing wrong?

try this, call function using event listener.

function minus_number() {         var  = document.queryselector("#spend");         var first_number = '50';         var second_number = '30';         var result = parseint(first_number) - parseint(second_number);         a.innerhtml = result;     } window.addeventlistener("load",minus_number());