$("#calculate").click(function(){ var items = $('#items').val().split(", "); var frequencies = $('#frequencies').val().split(", "); var sum = 0; var computation = 0; var size = 0; for (var i = 0; i < items.length; i++) { sum += parseFloat(items[i]) * parseFloat(frequencies[i]); size += parseFloat(frequencies[i]); } if(items && items.length > 0 && items[0] !== "") { computation = sum / size; } $('#result').text(parseFloat(computation).toFixed(2)); }); $("input").change(function(){ var isInvalid = $('#itemDiv').hasClass('is-invalid') || $('#frequencyDiv').hasClass('is-invalid'); if(isInvalid){ $("#add").prop("disabled", true); }else{ $("#add").removeAttr('disabled'); } }); $("#add").click(function(){ var items = $('#items'); var item = $('#item').val(); var listOfItems = items.val(); var frequencies = $('#frequencies'); var frequency = $('#frequency').val(); var listOfFrequencies = frequencies.val(); if(item && item.length > 0 && frequency && frequency.length > 0){ if(listOfItems && listOfItems.length > 0){ listOfItems += ', ' + item; listOfFrequencies += ', ' + frequency; }else{ listOfItems = item; listOfFrequencies = frequency; } $('#itemList').append("" + item + ""); $('#frequencyList').append("" + frequency + ""); } items.val(listOfItems); frequencies.val(listOfFrequencies); });

Enter Item & Frequency and Press Add Button.

Number required!
Number required!
Items
Frequency