JSFiddle - React, Tailwind, and code Playground

by David Joseph Guzsik

HTML

<label><input type="checkbox" onclick="calculateSectedDues(this,5)" name="Scarf"> <span>Scarf</span><label><br>
<label><input type="checkbox" onclick="calculateSectedDues(this,10)" name="Hat"> <span>Hat</span><label><br>
<label><input type="checkbox" onclick="calculateSectedDues(this,20)" name="Jacket"> <span>Jacket</span><label><br>

<span id="value">Total: $0<br>Discount: $0<br>New total: $0</span>

JavaScript

var prices = [];

function remove(arr,itm){
    var indx = arr.indexOf(itm);
    if (indx !== -1){
        arr.splice(indx,1);
    }
}

function calculateSectedDues(checkbox, amount) {
    if (checkbox.checked === true) {
        prices.push(amount);
    } else {
        remove(prices, amount);
    }

    var total = 0;
    for (var i = 0, len = prices.length; i < len; i++)
        total += prices[i];

    var min = prices.slice().sort(function(a,b){return a-b})[0];
    if(typeof min === 'undefined') min = 0;

    var withDiscount = total - min;
    var discountAmount = withDiscount - total;
    
    //document.grad_enroll_form.total.value = total;
    document.querySelector("#value").innerHTML = "Total: $"+total+'<br>';
    document.querySelector("#value").innerHTML += "Discount: $"+discountAmount+'<br>';
    document.querySelector("#value").innerHTML += "New total: $"+withDiscount+'<br>';
}