Please, can anybody tell me how can I access to the value of "41" in this inner script of a website? I just tried this, but it doesnt work

I tried with:

var elem = document.getElementById("back-in-stock-helper");

I only need the number 41, and the example code I need to access is this

<script id="back-in-stock-helper">
  var _BISConfig = _BISConfig || {};
  _BISConfig.product.variants[0]['inventory_quantity'] = 41;
</script>

Thanks!

Solved:

var elem = document.getElementById("back-in-stock-helper");

var elem2 = elem.textContent;

var ult_pos = elem2.lastIndexOf('=');

var stock = elem2.substring(ult_pos);