Develop Reference

adding click events to divs to change hidden input values

I am trying to get two divs to act as checkboxes (so that users can select 0 or all) that will influence hidden input values for a total that starts at 0. I am targetting the clicked divs by toggling a bootstrap color class to show user which has been chosen and - based on that class - add values to the hidden total input values below. I can get the totals to change outright, but I am trying to add to and subtract from the totals based on what is clicked/unclicked. Right now my code is returning an "Uncaught TypeError: Cannot set property 'value' of null". Any help you can give will be greatly appreciated!
$(document).ready(function() {
$('.select-class').on('click', function() {
//toggle clicked divs to show what's been selected
$(this).toggleClass('color');
//add values to total(0) if divs are clicked (have color class)
if (this.classList.contains('color')) {
//add1:
var addTotal1 = Number(document.getElementsByName('total1').value);
var addSingle1 = Number(document.getElementById(this.id.toString() + 'add1').value);
addTotal1 += addSingle1;
document.getElementById('totaladd1').value = addTotal1.toString();
//add2:
var addTotal2 = Number(document.getElementsByName('total2').value);
var addSingle2 = Number(document.getElementById(this.id.toString() + 'add2').value);
addTotal2 += addSingle2;
document.getElementById('totaladd2').value = addTotal2.toString();
//add3:
var addTotal3 = Number(document.getElementsByName('total3').value);
var addSingle3 = Number(document.getElementById(this.id.toString() + 'add3').value);
addTotal3 += addSingle3;
document.getElementById('totaladd3').value = addTotal3.toString();
}
//Subtract values if divs are unclicked (don't have color class)
if (!this.classList.contains('color')) {
//add1:
var addTotal1 = Number(document.getElementsByName('total1').value);
var addSingle1 = Number(document.getElementById(this.id.toString() + 'add1').value);
addTotal1 -= addSingle1;
document.getElementById('totaladd1').value = addTotal1.toString();
//add2:
var addTotal2 = Number(document.getElementsByName('total2').value);
var addSingle2 = Number(document.getElementById(this.id.toString() + 'add2').value);
addTotal2 -= addSingle2;
document.getElementById('totaladd2').value = addTotal2.toString();
//add3:
var addTotal3 = Number(document.getElementsByName('total3').value);
var addSingle3 = Number(document.getElementById(this.id.toString() + 'add3').value);
addTotal3 -= addSingle3;
document.getElementById('totaladd3').value = addTotal3.toString();
}
})
});
<div class="row p-lg-5">
<div id="div1" class="select-class">
<p>Content</p>
<!--hidden values-->
<div class="d-none">
<input type="number" class="add1" id="div1add1" value="1" />
<input type="number" class="add2" id="div1add2" value="45" />
<input type="number" class="add3" id="div1add3" value="4" />
</div>
</div>
<div id="div2" class="select-class">
<p>Content</p>
<!--hidden values-->
<div class="d-none">
<input type="number" class="add1" id="div2add1" value="3" />
<input type="number" class="add2" id="div2add2" value="20" />
<input type="number" class="add3" id="div2add3" value="3" />
</div>
</div>
</div>
<!--hidden totals-->
<div class="d-none">
<input id="totaladd1" type="number" name="total1" value="0" />
<input id="totaladd2" type="number" name="total2" value="0" />
<input id="totaladd3" type="number" name="total3" value="0" />
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

Set your add inputs as disabled by default
Add a data-total="" to every total input. Inside the data place the add-inputs-pairs selector i.e: ".add_1" etc...
Toggle class on click and perform a search for the non disabled add inputs, reducing their values to an accumulated number. Set that number as the iterating total input value
jQuery(function($) {
function calculateTot() {
$('[data-total]').each(function() {
const pair = $(this.dataset.total).not(':disabled').get();
$(this).val(pair.reduce((n, el) => (n += +el.value, n), 0))
});
}
$('.select-class').on('click', function() {
$(this).toggleClass('is-selected');
$(this).find('input').prop('disabled', !$(this).is('.is-selected'));
calculateTot();
}).find('input').prop('disabled', true); // Make inputs disabled by default
calculateTot(); // Calculate also on DOM ready
});
.select-class {cursor:pointer; padding:8px; border-radius:1em; border:1px solid #000;}
.is-selected {background:#0bf;}
.d-none {display:none;}
<div class="row p-lg-5">
<div id="div1" class="select-class">
Content 1 - Select me
<div class="d-none">
<input type="number" class="add_1" value="1" />
<input type="number" class="add_2" value="45" />
<input type="number" class="add_3" value="4" />
</div>
</div>
<div id="div2" class="select-class">
Content 2 - Select me
<div class="d-none">
<input type="number" class="add_1" value="3" />
<input type="number" class="add_2" value="20" />
<input type="number" class="add_3" value="3" />
</div>
</div>
</div>
<div> <!-- class="d-none" -->
<input data-total=".add_1" type="number" name="total1" />
<input data-total=".add_2" type="number" name="total2" />
<input data-total=".add_3" type="number" name="total3" />
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

How to get input submission to stay on screen instead of flashing across

I am currently trying to create a tip calculator app using JS, HTML, and CSS. My issue is that the input value is submitted when the button is clicked, but once submitted, the value just flashes for less than a second, then it vanishes. I would like for the value to stay on the screen once submitted.
let dinTotal = document.querySelector('#cost');
let dinService = document.querySelector('#service');
let dinSize = document.querySelector('#size');
let calcBtn = document.querySelector('button');
let total = 0;
let amount = document.querySelector('#amount')
calcBtn.addEventListener('click', function() {
if(dinTotal.value >= 50 && dinService.value < 5 && dinSize.value < 5) {
total = (dinTotal.value * 0.10) + dinTotal.value ;
amount.textContent = total;
}
})
<form>
<h1>Tip & Dip✌️</h1>
<hr>
<!-- Bill Section -->
<div>
<label for='cost'>Dinning amount</label>
</div>
<input name='cost' id='cost' type='number' placeholder='$' required>
<!-- Service Section-->
<div class='top-space'>
<label for='service'>How was the service</label>
</div>
<input name='service' id='service' type='number' placeholder='rate 1-10' required>
<!-- Party Size-->
<div class='top-space'>
<label for='size'>Party Size</label>
</div>
<div>
<input name='size' id='size' type='number' required>
</div>
<div class='top-space'>
<button>LET'S CALCULATE...</button>
</div>
<hr>
<h2>Total: $<span id='amount'>0</span></h2>
</form>

The default behavior of a button is to submit the form. When a form submits, if you don't stop it, it will unload the current page and submit the data to its action URL. With no action attribute, a form submits to the current page, causing your reload.
Set the type attribute on your button to button to prevent it from being a submit button.
<button type="button">LET'S CALCULATE...</button>

use the preventDefualt() method of the event callback
calcBtn.addEventListener('click', function(event) {
event.preventDefault()
}
Full working snippet (though it only updates for size and value of less than 5 and checks greater than 50 I hope you know)
let dinTotal = document.querySelector('#cost');
let dinService = document.querySelector('#service');
let dinSize = document.querySelector('#size');
let calcBtn = document.querySelector('button');
let total = 0;
let amount = document.querySelector('#amount')
calcBtn.addEventListener('click', function(event) {
event.preventDefault()
if(dinTotal.value >= 50 && dinService.value < 5 && dinSize.value < 5)
{
total = (dinTotal.value * 0.10) + dinTotal.value ;
console.log(total)
amount.textContent = total;
}
})
<form>
<h1>Tip & Dip✌️</h1>
<hr>
<div>
<label for='cost'>Dinning amount</label>
</div>
<input name='cost' id='cost' type='number' placeholder='$' required>
<div class='top-space'>
<label for='service'>How was the service</label>
</div>
<input name='service' id='service' type='number' placeholder='rate 1-10' required>
<div class='top-space'>
<label for='size'>Party Size</label>
</div>
<div>
<input name='size' id='size' type='number' required>
</div>
<div class='top-space'>
<button>LET'S CALCULATE...</button>
</div>
<hr>
<h2>Total: $<span id='amount'>0</span></h2>
</form>

Why does this return NaN

no matter what i try i cant get the function to run properly
ive tried checked that the inputs are numbers, and only the output is giving me NaN. ive tried putting parseInt around the inputs, but the inputs eem to be working correctly. its probably a small newb mistake, thanks for your time anyway!
const principle=parseInt(document.getElementsByClassName('principle').value);
const rate = parseInt(document.getElementsByClassName('.rate').value);
const payments = parseInt(document.getElementsByClassName('payments').value);
let interest;
function calculate() {
console.log(typeof(principle));
console.log(typeof(rate));
console.log(typeof(payments));
interest = (rate / payments) * principle;
console.log(interest);
};
<body>
<h1>interest calculator</h1>
<div class="container">
<div class="row">
<div class="col-4-md">
initial amount <input type="number" name="" value="" class="principle px-3">
</div>
<div class="col-4-md">
interest rate <input type="number" name="" value="" class="rate px-3">
</div>
<div class="col-4-md">
Number of payments <input type="number" name="" value="" class="payments px-3">
</div>
<button type="submit" name="button" onclick="calculate()">Submit</button>
</div>
</div>
i just want the output to be a number

Here is a working code after modifications/fixes:
<html>
<head>
<script>
let interest;
function calculate() {
const principle=parseInt((document.getElementsByClassName('principle')[0]).value);
const rate = parseInt((document.getElementsByClassName('rate')[0]).value);
const payments = parseInt((document.getElementsByClassName('payments')[0]).value);
console.log(typeof(principle));
console.log(principle);
console.log(typeof(rate));
console.log(rate);
console.log(typeof(payments));
console.log(payments);
interest = (rate / payments) * principle;
console.log(interest);
};
</script>
</head>
<body>
<h1>interest calculator</h1>
<div class="container">
<div class="row">
<div class="col-4-md">
initial amount <input type="number" name="" value="" class="principle px-3">
</div>
<div class="col-4-md">
interest rate <input type="number" name="" value="" class="rate px-3">
</div>
<div class="col-4-md">
Number of payments <input type="number" name="" value="" class="payments px-3">
</div>
<button type="submit" name="button" onclick="calculate()">Submit</button>
</div>
</div>
</body>
</html>

You have 2 mistakes in your JS.
1) getByClassName return an array of element, so you must select which element you want in your case, since you have only one element of each, you can easily do document.getElementsByClassName('rate')[0]
2) at the moment you load the page, you assign your values. but when you fill the document, and calculate, you don't check the value again. so they are still undefined.
if you fix everything you will get this JS
const principle$ = document.getElementsByClassName('principle')[0];
const rate$ = document.getElementsByClassName('rate')[0];
const payments$ = document.getElementsByClassName('payments')[0];
let interest;
function calculate() {
console.log(principle$, principle$.value)
const principle = parseInt(principle$.value);
const rate = parseInt(rate$.value);
const payments = parseInt(payments$.value);
interest = (rate / payments) * principle;
console.log(interest);
};
https://codepen.io/crocsx-the-styleful/pen/MWgOLgm

Becuase typeof NaN is also a number
console.log(typeof NaN)
When you JS code execute the variable are outside the function so the are calculated with as soon as your script load, during that time your inputs hold empty string
console.log(parseInt(''), typeof parseInt(''))
You need to move your variables inside the function so they will be evaluated when the submit button is pressed
function calculate() {
const principle = parseInt(document.getElementsByClassName('principle')[0].value);
const rate = parseInt(document.getElementsByClassName('rate')[0].value);
const payments = parseInt(document.getElementsByClassName('payments')[0].value);
let interest;
console.log(typeof(principle));
console.log(typeof(rate));
console.log(typeof(payments));
interest = (rate / payments) * principle;
console.log(interest);
};
<body>
<h1>interest calculator</h1>
<div class="container">
<div class="row">
<div class="col-4-md">
initial amount <input type="number" name="" value="" class="principle px-3">
</div>
<div class="col-4-md">
interest rate <input type="number" name="" value="" class="rate px-3">
</div>
<div class="col-4-md">
Number of payments <input type="number" name="" value="" class="payments px-3">
</div>
<button type="submit" name="button" onclick="calculate()">Submit</button>
</div>
</div>
Also you're using getElementsByClassName which returns a node list, you need to access particular node using index

JS/jQuery: fire onchange from a disabled/readonly input without using button

The goal is to get the total Qty for the whole year.
The user will input numbers into 3 different textboxes(Jan,Feb,Mar), then the sum will be displayed into a disabled textbox(Quarter1).
Now I have 4 instances of these knowing we have 4 quarters/year.
I can easily display the sum per quarter, by using the onchange() function attached to the textboxes.
Now I am having issues getting the sum from the 4 disabled textboxes, knowing we can't use the onchange() on it because it's disabled.
I have searched and probably getting results only when a button is used.
TLDR: I am trying to display the sum from the four disabled textboxes to another textbox automatically, without the user clicking any button(just like firing the onchange event)
I have tried this one, wherein I tried to display the value of the first quarter to the total, and not working:
$(document).ready(function() {
$('input[id$=yearlyTotal]').bind("displaytotal", function() {});
$('#qtr1').change(function() {
var mos = document.getElementsByClassName("quantityA");
var mosCount = mos.length;
var total = 0;
for (var i = 0; i < mosCount; i++) {
total = total + parseInt(mos[i].value);
}
$('input[id$=yearlyTotal]').val(total).trigger('displaytotal');
});
});
Hope it's possible, thanks in advance
EDIT: Added UI
Showing Q1 (its just the same for the 4 qtrs)
<div class="form-group col-md-6">
<label class="col-sm-1 control-label">Jan:</label>
<div class="col-sm-2 small">
<input type="number" min="0" id="col3" class="form-control input-sm monthly" data-q="q1" name="January" />
</div>
<label class="col-sm-1 control-label">Feb:</label>
<div class="col-sm-2 small">
<input type="number" min="0" id="col4" class="form-control input-sm monthly" data-q="q1" name="February" />
</div>
<label class="col-sm-1 control-label">Mar:</label>
<div class="col-sm-2 small">
<input type="number" min="0" id="col5" class="form-control input-sm monthly" data-q="q1" name="March" />
</div>
<label class="col-sm-1 control-label">Q1:</label>
<div class="col-sm-2 small">
<input type="text" min="0" id="q1" class="form-control input-sm quarter" name="q1" style="background-color: #b3dcf5;" disabled />
</div>
</div>
This is the div for the total Qty
<div class="col-md-6">
<label class="col-sm-3 control-label" id="">Total Quantity:</label>
<div class="col-sm-3 small">
<input type="text" id="final" class="form-control input-sm" name="TotalQuantity" value="0" disabled />
</div>
</div>

Method 1:
Basically, what you need to do is to trigger the change event for the disabled quarter fields programatically, using jQuery .trigger() function.
As I don't know how your HTML is structured -this why it is always recommended to provide MCVE example- I made a demo example and I've done things differently, like below:
jsFiddle 1
var monthly = $('.monthly'),
Qrt = $('.quarter');
monthly.on('change, input', function() {
var $th = $(this),
// depending on the value of the data-q attribute, we pick
// all input fields with the same data-q as an array, then
//loop through them adding their values up
q = $th.attr('data-q'),
qArray = $th.parent().children('input[data-q="' + q + '"]'),
tempSum = 0;
for (var i = 0, ln = qArray.length; i < ln; i++) {
tempSum += +$(qArray[i]).val();
}
// we pick the corresponding quarter sum field, again depending
// on the value of the data-q attritues, and update its value, then
// we trigger the change event of this quarter sum field.
$('#' + q).val(tempSum).trigger('change'); // here you trigger it
});
Qrt.on('change', function() {
var qSum = 0;
for (var i = 0, ln = Qrt.length; i < ln; i++) {
qSum += +$(Qrt[i]).val();
}
$('#final').val(qSum);
});
.monthly { width: 32%; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<h3>Grand Total:</h3><input type="text" id="final" disabled><hr>
<h3>1st Q:</h3>
<input type="text" class="monthly" data-q="q1">
<input type="text" class="monthly" data-q="q1">
<input type="text" class="monthly" data-q="q1">
<br>Sum:<input id="q1" type="text" class="quarter" disabled>
<h3>2nd Q:</h3>
<input type="text" class="monthly" data-q="q2">
<input type="text" class="monthly" data-q="q2">
<input type="text" class="monthly" data-q="q2">
<br>Sum:<input id="q2" type="text" class="quarter" disabled>
<h3>3rd Q:</h3>
<input type="text" class="monthly" data-q="q3">
<input type="text" class="monthly" data-q="q3">
<input type="text" class="monthly" data-q="q3">
<br>Sum:<input id="q3" type="text" class="quarter" disabled>
<h3>4th Q:</h3>
<input type="text" class="monthly" data-q="q4">
<input type="text" class="monthly q-4th" data-q="q4">
<input type="text" class="monthly q-4th" data-q="q4">
<br>Sum:<input id="q4" type="text" class="quarter" disabled>
Method 2:
since any change you make to any .monthly field will change the corresponding value of quarter sum, and thus it'll also affect the value of the yearly sum, you don't need to capture the change event of the disabled quarter sum fields, just loop through their values and update the value of the yearly field, all should be done inside the on('change') event of the .monthly fields, like below:
jsFiddle 2
jQuery
var monthly = $('.monthly'),
Qrt = $('.quarter');
monthly.on('change, input', function() {
var $th = $(this),
q = $th.attr('data-q'),
qArray = $th.parent().children('input[data-q="' +q+ '"]'),
tempSum = 0,
qSum = 0;
for (var i = 0, ln = qArray.length; i < ln; i++) {
tempSum += +$(qArray[i]).val();
}
$('#' + q).val(tempSum);
// code below
for (var i = 0, ln = Qrt.length; i < ln; i++) {
qSum += +$(Qrt[i]).val();
}
$('#final').val(qSum);
});
Update:
For the updated HTML in the OP, replace qArray line with this one:
$th.parents('.form-group').find('input[data-q="' + q + '"]')`,
Note parents() is with "s" letter, unlike the former parent() which moves up a single level up the DOM, it does " search through the ancestors of these elements in the DOM tree and construct a new jQuery object from the matching elements ordered from immediate parent on up. ", so it travels up until we reach the matchng parent, here it is .form-group.
Then instead of children(), we use find().
jsFiddle 3

Please find the below code (Finding the total for quarter A & quarter B) for your reference. Please use same methodology for other quarters.
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
/* FINDING THE QUARTER A AND QUARTER B */
function findingQuaterTotal () {
/* LOADING QUARTER A AND FINDING ITS TOTAL - STARTS */
var mosQuarterA = document.getElementsByClassName("quarterA"),
mosCountQuarterA = mosQuarterA.length,
totalQuarterA = 0,
i = 0;
for (i = 0; i < mosCountQuarterA; i++) {
totalQuarterA = totalQuarterA + parseInt(mosQuarterA[i].value);
}
/* ADDING INTO QUATER A DISABLED TEXTBOX */
$("#quarterA").val(totalQuarterA);
/* LOADING QUARTER A AND FINDING ITS TOTAL - ENDS */
/* LOADING QUARTER B AND FINDING ITS TOTAL - STARTS */
var mosQuarterB = document.getElementsByClassName("quarterB"),
mosCountQuarterB = mosQuarterB.length,
totalQuarterB = 0;
for (i = 0; i < mosCountQuarterB; i++) {
totalQuarterB = totalQuarterB + parseInt(mosQuarterB[i].value);
}
/* ADDING INTO QUARTER B DISABLED TEXTBOX */
$("#quarterB").val(totalQuarterB);
/* LOADING QUARTER B AND FINDING ITS TOTAL - ENDS */
/* TRIGGERING CHANGE EVENT IN THE DISABLED TEXTBOX WHOSE ID STARTS WITH QUARTER.*/
$("input[id^='quarter']").trigger("change");
};
/* ABOVE CHANGE TRIGGER WILL CALL BELOW EVENTS - STARTS */
$("input[id^='quarter']").change(function () { $("#final").val(parseInt($("#quarterA").val())+parseInt($("#quarterB").val()));
});
/* ABOVE CHANGE TRIGGER WILL CALL BELOW EVENTS - ENDS */
/* IF ANY VALUE CHANGES IN MONTH TEXT BOX, FLLWING FUNCTION WILL BE CALLED - STARTS */
$("input[id^='month']").on("change keyup",function () {
findingQuaterTotal();
});
findingQuaterTotal();
/* IF ANY VALUE CHANGES IN MONTH TEXT BOX, FLLWING FUNCTION WILL BE CALLED - ENDS */
});
</script>
</head>
<body>
<h2>Quater A</h2>
Jan - <input type="number" id="month1" value="6" class="quarterA"></br>
Feb - <input type="number" id="month2" value="16" class="quarterA"></br>
March - <input type="number" id="month3" value="25" class="quarterA"></br>
Quater A Total - <input type="number" id="quarterA" value="" disabled></br>
<br/><br/>
<h2>Quater B</h2>
April - <input type="number" id="month4" value="6" class="quarterB"></br>
May - <input type="number" id="month5" value="16" class="quarterB"></br>
June - <input type="number" id="month6" value="25" class="quarterB"></br>
Quater B Total - <input type="number" id="quarterB" value="" disabled></br>
Quarter A and Quarter B total - <input type="number" id="final" value="" disabled>
</body>
</html>

Display and calculate input number

How do i automatically display every time I input number and calculate it.
Then the pick button will trigger to calculate the price, my base price would be 100. so if its 2 layers it will be 200 ,
<br> Layer <input type="number" min="1" id="cake_layer" name="cake_layer" /> <!-- onchange="updateTotal()" -->
<input type="button" value="Pick" id="choose" />
<br>
Layer inputed <div class="layer_display"> </div>
<br>
Layer Amount <div class="layer_amt"> </div>
I really need help. thank you !!!

Is this what you want to do?
var cakeLayer = document.getElementById("cake_layer"),
price = 100,
layerDisplay = document.getElementsByClassName("layer_display")[0],
layerAmt = document.getElementsByClassName("layer_amt")[0];
cakeLayer.onchange = function(event) {
var amount = this.value || 0,
totalPrice = amount * price;
layerDisplay.innerText = totalPrice;
layerAmt.innerText = amount;
}
<input type="number" min="1" id="cake_layer" name="cake_layer" />
<!-- onchange="updateTotal()" -->
<input type="button" value="Pick" id="choose" />
<br> total price
<div class="layer_display"> </div>
<br> Layer Amount
<div class="layer_amt"> </div>

You can achieve this by using JavaScript or jQuery. That's the only way to manipulate the DOM.
See this working jsfiddle I made:
https://jsfiddle.net/jw6q53fz/1/
HMTL
<div>
<label for="cake_layer">Layer</label>
<input type="number" class="cake_layer" name="cake_layer" id="cake_layer"/>
<button id="choose">Pick</button>
</div>
<div>
<p>Layer inputed: <span class="layer_display"> </span></p>
<p>Layer Amount: <span class="layer_amt"> </span></p>
</div>
jQuery
$('#choose').on('click', function(){
var cakeLayerValue = $('#cake_layer').val();
$('.layer_display').html(cakeLayerValue);
$('.layer_amt').html(cakeLayerValue * 100);
});