Educator calculate unweighted or weighted average mark

unweighted-average.js

var x = Array.prototype.slice.call(document.querySelectorAll('.datatable > tbody > tr > td:nth-child(4n)'), 0)
  .filter(function(elem) {return elem.textContent != ''; })
  .map(function(elem) {return parseFloat(elem.textContent); });


var total = x.reduce(function(a, b) {return a+b;})

console.info(total/x.length)

weighted-average.js

var x = Array.prototype.slice.call(document.querySelectorAll('.datatable > tbody > tr > td:nth-child(4n),.datatable > tbody > tr > td:nth-child(6n)', 0));
var y = [];

for (var i = 0; i < x.length; i+=2) 
  if (x[i].textContent != '' && x[i + 1] && x[i + 1].textContent) 
    y.push(parseFloat(x[i].textContent) * parseFloat(x[i + 1].textContent));

var gotEc = parseInt(document.getElementById("id47").textContent.split("er ")[1].split(" behaald.")[0])
var total = y.reduce(function(a, b) {return a+b;})

console.info(total/gotEc)