Develop Reference

How do I dynamically change the ID to do calculations?

I have the same form duplicated and triplicated, and depending on clicks on a button, they appear. What I want to do is to be able to make calculations, for example, of the cell Quantity and Unit_Price a multiplication and that the result is reflected in Total Price.
I need the Quantity and Unit_Price IDs to change dynamically so that the result is displayed per cell in their respective Total Price. I already wrote a piece of code that takes the number of each cell, the problem is that I don't know how to put it with the ID so that it is dynamic (the number should change depending on the cell it is in)
This is where I don't know how the code should be:
function multiplicar() {
let quantity = parseInt(document.getElementById('id__form-1-quantity').value);
let unit_price = document.getElementById('id__form-1-unit_price').value;
let total_price = document.getElementById('id__form-1-total_price');
total_price.value = quantity * unit_price;
}
function updateEmptyFormIDs(element, totalForms) {
var thisInput = element
var currentName = element.attr('name')
var newName = currentName.replace(/__prefix__/g, totalForms)
thisInput.attr('name', newName)
thisInput.attr('id', "id__" + newName)
var newFormRow = element.closest(".part-form");
var newRowId = "row_id_" + newName
newFormRow.attr("id", newRowId)
newFormRow.addClass("new-parent-row")
var parentDiv = element.parent();
parentDiv.attr("id", "parent_id_" + newName)
var inputLabel = parentDiv.find("label")
inputLabel.attr("for", "id_" + newName)
return newFormRow
}
function addForm() {
//$('.add-new-form').click(function(e){
var formId = "id_form-TOTAL_FORMS"
var emptyRow = $("#empty-row").clone();
emptyRow.attr("id", null);
var totalForms = parseInt($('#' + formId).val());
var newFormRow;
emptyRow.find("input,select,textarea").each(function() {
newFormRow = updateEmptyFormIDs($(this), totalForms)
})
$(".part-form:last").after(newFormRow)
$('#' + formId).val(totalForms + 1);
}
<table>
<tr>
<td id="parent_id_form-1-quantity">
<input type="number" name="form-1-quantity" class="form-control" id="id__form-1-quantity">
</td>
<td id="parent_id_form-1-unit_price">
<input type="number" name="form-1-unit_price" class="form-control" onchange="multiplicar()" id="id__form-1-unit_price">
</td>
<td id="parent_id_form-1-total_price">
<input type="number" name="form-1-total_price" class="form-control" id="id__form-1-total_price">
</td>
</tr>
</table>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

Html table add column with javascript

I am obviously very new to JS. I need to solve a problem where i can't change the HTML and CSS-file. From the HTML-file I am supposed to:
add a column with the header "Sum". (Already did that)
add a row att the bottom with the div id "sumrow". (Did that as well)
add a button at the end. (Did that)
add the total from columns "Price and Amount" into column "Sum" when button is clicked
(This where I am lost)
And like I said I can't change anything in HTML and CSS-files.
// Create a newelement and store it in a variable
var newEl = document.createElement('th');
//Create a text node and store it in a variable
var newText = document.createTextNode('Summa');
//Attach the newtext node to the newelement
newEl.appendChild(newText);
//Find the position where the new element should be added
var position = document.getElementsByTagName('tr')[0];
//Insert the newelement into its position
position.appendChild(newEl);
// Find a <table> element with id="myTable":
var table = document.getElementById("pricetable");
// Create an empty <tr> element and add it to the 1st position of the table:
var row = table.insertRow(-1);
// Insert new cells (<td> elements) at the 1st and 2nd position of the "new" <tr> element:
var cell1 = row.insertCell(0);
var cell2 = row.insertCell(1);
var cell3 = row.insertCell(2);
var cell4 = row.insertCell(3);
var cell5 = row.insertCell(4);
var cell6 = row.insertCell(5);
// Add some text to the new cells:
cell1.innerHTML = "";
cell2.innerHTML = "";
cell3.innerHTML = "";
cell4.innerHTML = sumVal;
cell5.innerHTML = "";
cell6.innerHTML = "";
//Puts divid sumrow
row.setAttribute("id", "sumrow");
var table = document.getElementById("pricetable"), sumVal = 0;
for(var i = 1; i < table.rows.length; i++)
{
sumVal = sumVal + parseInt(table.rows[i].cells[3].innerHTML);
}
//Creates button
var button = document.createElement("button");
button.innerHTML = "Beräkna pris";
// 2. Append somewhere
var body = document.getElementsByTagName("tbody")[0];
body.appendChild(button);
button.addEventListener("click", medelVarde, true);
button.addEventListener("click", raknaUtMedelvarde, true);
button.setAttribute("class", "btn-primary");
function medelVarde(celler){
var summa = 0;
for(var i = 3; i < celler.length -1; i++){ //Räknar igenom från cell nr 4
var nuvarandeVarde = celler[i].firstChild.nodeValue;
summa = summa + parseInt(nuvarandeVarde);
}
var medel = summa / 1;
return medel;
}
function raknaUtMedelvarde(){
var tabell = document.getElementById("pricetable");
var rader = tabell.getElementsByTagName("tr");
for(var i = 1; i < rader.length; i++){
var tabellceller = rader[i].getElementsByTagName("td"); //Pekar på de td-element som vi har hämtat
var medel = medelVarde(tabellceller);
var medeltext = document.createTextNode(medel);
var medelelement = tabellceller[tabellceller.length - 1];
var row2 = table.insertRow(-1);
medelelement.appendChild(medeltext.cloneNode(true));
.table {
background: white;
}
tr#sumrow {
background-color: #cce4ff;
}
tr#sumrow td:first-child::after{
content: "\a0";
}
<!DOCTYPE html>
<html lang="sv">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<title>Handling calculations and tables</title>
<link rel="stylesheet" type="text/css" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" />
<link rel="stylesheet" type="text/css" href="style/style.css" />
</head>
<body>
<div class="container">
<div id="header" class="text-center px-3 py-3 pt-md-5 pb-md-4 mx-auto">
<h1 class="display-4">Home Electronics</h1>
<p class="lead">Excellent prices on our hone electronics</p>
</div>
<div id="content">
<table id="pricetable" class="table table-hover">
<thead class="thead-dark">
<tr>
<th>Articlenr</th>
<th>Producttype</th>
<th>Brand</th>
<th>Price</th>
<th>Amount</th>
</tr>
</thead>
<tbody>
<tr>
<td>23456789</td>
<td>Telephone</td>
<td>Apple</td>
<td>6500</td>
<td>
<input type="text" size="3" value="1" />
</td>
</tr>
<tr>
<td>22256289</td>
<td>Telephone</td>
<td>Samsung</td>
<td>6200</td>
<td>
<input type="text" size="3" value="1" />
</td>
</tr>
<tr>
<td>24444343</td>
<td>Telephone</td>
<td>Huawei</td>
<td>4200</td>
<td>
<input type="text" size="3" value="1" />
</td>
</tr>
<tr>
<td>19856639</td>
<td>Tablet</td>
<td>Apple</td>
<td>4000</td>
<td>
<input type="text" size="3" value="1" />
</td>
</tr>
<tr>
<td>39856639</td>
<td>Tablet</td>
<td>Samsung</td>
<td>2800</td>
<td>
<input type="text" size="3" value="1" />
</td>
</tr>
<tr>
<td>12349862</td>
<td>Tablet</td>
<td>Huawei</td>
<td>3500</td>
<td>
<input type="text" size="3" value="1" />
</td>
</tr>
</tbody>
</table>
</div>
</div>
<!-- add this script as snippet in this question -->
<!-- <script src="scripts/calculate.js"></script> -->
</body>
</html>
Or code is available on https://jsfiddle.net/cmyr2fp6/

button.addEventListener("click", medelVarde, true);
button.addEventListener("click", raknaUtMedelvarde, true);
For the button click event listener, you don't have to add the medelVarde function.
Also, speaking of that function, I'm not really sure what's happening there. Are you trying to multiply the price and the amount? If so, you can just get the price cell's text and multiply it by the amount input's value (converting to Number the values before multiplying).
const [,,, priceCell, amountCell, sumCell] = row.querySelectorAll('td');
const price = Number(priceCell.innerText);
const amount = Number(amountCell.querySelector('input').value);
const sum = price * amount;
The [,,, priceCell, amountCell, sumCell] is just a short-hand for getting the cells you want from the row (destructuring assignment. querySelectorAll returns a NodeList wherein you can get the element by index.
function setUp() {
// Set up table.
const table = document.getElementById('pricetable');
const headerRow = table.querySelector('thead tr');
const sumHeader = headerRow.insertCell();
const tbody = table.querySelector('tbody');
const sumTotalRow = tbody.insertRow();
const sumTotalCell = sumTotalRow.insertCell();
sumHeader.innerText = 'Summa';
sumTotalCell.colSpan = '5';
sumTotalCell.innerText = 'Total';
tbody.querySelectorAll('tr').forEach(row => row.insertCell());
// Set up button.
const btn = document.createElement('button');
btn.innerText = 'Beräkna pris';
btn.addEventListener('click', () => {
let total = 0;
tbody.querySelectorAll('tr').forEach((row, i, arr) => {
if (i < arr.length - 1) {
const [,,, priceCell, amountCell, sumCell] = row.querySelectorAll('td');
const price = Number(priceCell.innerText);
const amount = Number(amountCell.querySelector('input').value);
const sum = price * amount;
sumCell.innerText = sum;
total += sum;
} else {
const totalCell = row.querySelector('td:last-child');
totalCell.innerText = total;
}
});
});
document.body.appendChild(btn);
}
setUp();

Hey ZioPaperone welcome to the JS World :-)
First of all I would recommend to wrap you logic into functions, eg
appendRow() {
//put append row logic here
}
Now let's move on to your question, appending a column is a bit more of a trick then appending a row. You might noticed already that the DOM-Structure is a bit more complex. So for a row you could you correctly has added a node to your tbody.
For a column we need to learn how to create a cell and how we add an entry to the thead. We will use the insertCell() method to insert cells, for thead cells that won't work, so we need to add the th with createElement() and append it with appendChild()
function appendColumn() {
// insertCell doesn't work for <th>-Nodes :-(
var tableHeadRef = document.getElementById('pricetable').tHead; // table reference
var newTh = document.createElement('th');
tableHeadRef.rows[0].appendChild(newTh); // inser new th in node in the first row of thead
newTh.innerHTML = 'thead title';
// open loop for each row in tbody and append cell at the end
var tableBodyRef = document.getElementById('pricetable').tBodies[0];
for (var i = 0; i < tableBodyRef.rows.length; i++) {
var newCell = tableBodyRef.rows[i].insertCell(-1);
newCell.innerHTML = 'cell text'
}
}
EDIT:
To sum up values in col u can use the same approach. I broke down the nodes for better understanding. You also might want to add a check if your table data contains a number with isNaN().
function sumColumn(tableId, columnIndex) {
var tableBodyRef = document.getElementById(tableId).tBodies[0];
var sum = 0; // Initialize sum counter with 0
for (var i = 0; i < tableBodyRef.rows.length; i++) {
var currentRow = tableBodyRef.rows[i]; //access current row
var currentCell = currentRow.cells[columnIndex]; // look for the right column
var currentData = currentCell.innerHTML; // grab cells content
var sum += parseFloat(currentData); // parse content and add to sum
}
return sum;
}

Deleting a table row using row numbers in Javascript

I created a table that can add rows by filling in a form. Every row added to the table, get's a row number. Now I want to delete a certain row by putting in the row number in another input (using a deleteRow-function).
<table id="table">
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Points</th>
</tr>
</table>
<form action="" id="form" name="form">
First name: <input type="text" id="fnaam"> <br>
Last name: <input type="text" id="lnaam"><br>
Points: <input type="text" id="points">
</form>
<button type="button" id="addBtn">Voeg toe</button>
Fill in row number: <input type="text" id="deleteRowInput"> <br>
<button type="button" id="deleteBtn">Delete Row</button>
This is the Javascript I use. I created a deleteRow-function, but it's not working yet. Thanks!
var addBtn = document.getElementById('addBtn');
var deleteBtn = document.getElementById('deleteBtn');
addBtn.onclick = addRow;
deleteBtn.onclick = deleteRow;
var rowNumber = 0;
function addRow() {
//getting data from form
var form = document.getElementById('form');
var newData = [];
for(var i = 0; i < form.length; i++) {
newData[i] = form.elements[i].value;
}
if(validateForm() == true) {
rowNumber++;
//Put data in table
var table = document.getElementById('table');
var newRow = table.insertRow();
//Adding rownumber to row
newRow.innerHTML = `<tr><td><i>${rowNumber}</i></td><tr>`;
for(var i = 0; i < 3; i++) {
var newCell = newRow.insertCell(i);
newCell.innerHTML = newData[i];
}
}
form.reset();
}
function deleteRow() {
var table = document.getElementById('table');
var input = document.getElementById('deleteRowInput');
}
//validating form
function validateForm() {
var f = document.getElementById('form');
if(f.fnaam.value == '') {
alert('Please fill in first name!');
return false;
}
if(f.lnaam.value == '') {
alert('Please fill in last name!');
return false;
}
if(f.points.value == '') {
alert('Please fill in points!');
return false;
}
if(isNaN(f.points.value)) {
alert('Points should be a number!')
return false
}
return true;
}

To simplify matters, add a data- attribute to the tr elements containing the respective row number.
Modification in addNumber:
newRow.innerHTML = `<tr data-row-number="${rowNumber}"><td><i>${rowNumber}</i></td><tr>`;
The deleteRow function could look like this:
function deleteRow() {
let table = document.getElementById('table');
let input = document.getElementById('deleteRowInput');
let n_rowToDelete = input.value;
document.querySelector ( 'tr[data-row-number="' + n_rowToDelete + '"]' ).remove();
}
Watch out for:
having 1 table only.
not to delete the last row
... and be aware that after the first call to deleteRow there will neither be a contiguous list of row numbers nor will the row number mirror the position of the row in the sequence of table rows.

Javascript Delete row with checkbox

Hi i'm a beginner and I'm trying to do a simple CRUD Car apps but i cannot delete row with my function deleteRow().
I've create a function call deleteRow i add a checkbox in every row with the createElement method and i'm setting the Id attribute using the setAttribute() method.In my function i'm trying to get to the checkbox to see if its checked and if so using the deleteRow method to delete the row.
function addRow() {
/* check if its empty */
var brandValue = document.getElementById("brand").value;
var modelValue = document.getElementById("model").value;
if (brandValue == "" || modelValue == "") {
return alert("Make sure you enter a brand and a model!")
}
/* Add a row */
"use strict";
var table = document.getElementById("table");
var row = document.createElement("tr");
var td1 = document.createElement("td");
var td2 = document.createElement("td");
var td3 = document.createElement("INPUT");
td3.setAttribute("type", "checkbox");
td3.setAttribute("id", "cb");
td1.innerHTML = document.getElementById("brand").value;
td2.innerHTML = document.getElementById("model").value;
row.appendChild(td1);
row.appendChild(td2);
row.appendChild(td3);
table.children[0].appendChild(row);
document.getElementById('brand').value = "";
document.getElementById('model').value = "";
}
var temp = 1;
function deleteRow() {
for (var j = temp - 2; j >= 0; j--) {
if (document.table.cb[j].checked) {
document.getElementById("table").deleteRow(j + 1);
}
}
}
<input type="text" id="brand" placeholder="Add a brand">
<input type="text" id="model" placeholder="Add a Model">
<button type="button" onClick="addRow()" id="add">Update</button>
<button type="button" onClick="deleteRow()" id="delete">Delete</button>
<table id="table">
<div class="tableDiv">
<tr>
<th>Brands</th>
<th>Models</th>
<th>Select</th>
</tr>
</div>
</table>
Right now nothing happen when i'm trying to delete and i have nothing in the browser console.
Thanks for your help.

Try this:
const $brand = document.getElementById("brand")
const $model = document.getElementById("model")
const $table = document.getElementById("table")
function addRow() {
/* check if its empty */
if ($brand.value == "" || $model.value == "") {
return alert("Make sure you enter a brand and a model!")
}
let $row = document.createElement("tr");
let $td1 = document.createElement("td");
let $td2 = document.createElement("td");
let $td3 = document.createElement("input");
$td3.setAttribute("type", "checkbox");
$td1.innerHTML = $brand.value;
$td2.innerHTML = $model.value;
$row.appendChild($td1);
$row.appendChild($td2);
$row.appendChild($td3);
$table.children[0].appendChild($row);
$brand.value = "";
$model.value = "";
}
function deleteRow() {
let checkboxs = $table.querySelectorAll("input[type='checkbox']:checked")
checkboxs.forEach(checkbox => checkbox.parentElement.remove())
}
<input type="text" id="brand" placeholder="Add a brand"></input>
<input type="text" id="model" placeholder="Add a Model"></input>
<button type="button" onClick="addRow()" id="add">Update</button>
<button type="button" onClick="deleteRow()" id="delete">Delete</button>
</div>
<table id="table">
<div class="tableDiv" <tr>
<th>Brands</th>
<th>Models</th>
<th>Select</th>
</tr>
</div>
</table>

for (var j = temp - 2; j >= 0; j--) { this loop never starts due to temp being 1.
1 - 2 = -1 so the loop condition (j >= 0) is never true.

Your main mistake is that you don't need to iterate anything, you can select the checked elements directly.
Try using document.querySelector("#table input[type='checkbox']:checked")
Another thing is that now you are assigning the same id to multiple elements. This should not be done, it can lead to unexpected behavior. Consider using class or custom attribute instead

let checkboxes = document.querySelectorAll('input[type="checkbox"]:checked');
checkboxes.forEach(checkbox => checkbox.parentElement.parentElement.remove());

JS add rows to table. Rows appear and then disappear

I want to add a number of rows to a HTML table, and 9 cells to each row using a JS loop. The problem is that I see in the HTML doc for a short instant (miliseconds) what I want, but later it is erased. Why could it be? This is the code with the JS loop and the HTML.
function calcular() {
var cantidad = Number(document.getElementById("cantidad").value);
var numAnos = Number(document.getElementById("numAnos").value);
var numMeses = Number(document.getElementById("numMeses").value);
var fecha = document.getElementById("fecha");
//Meses
var numFilas = numAnos * 12 + numMeses;
var table = document.getElementById("tablaDatos");
alert(Number(numFilas));
for (var i = 0; i < Number(numFilas); i++) {
alert(table.rows.length);
var newTR = table.insertRow(table.rows.length);
//var row = table1.insertRow(table1.rows.length);
//num cuota
var newTD0 = newTR.insertCell(0);
newTD0.innerHTML = i;
var newTD1 = newTR.insertCell(1);
var newTD2 = newTR.insertCell(2);
var newTD3 = newTR.insertCell(3);
var newTD4 = newTR.insertCell(4);
var newTD5 = newTR.insertCell(5);
var newTD6 = newTR.insertCell(6);
var newTD7 = newTR.insertCell(7);
var newTD8 = newTR.insertCell(8);
}
}
<form action="" name="formDatosInicio">
Cantidad: <input type="text" id="cantidad" name="cantidad"><br> Num años: <input type="text" id="numAnos" name="numAnos"><br> Num meses: <input type="text" id="numMeses" name="numMeses"><br> Fecha:
<input type="date" id="fecha" name="fecha"><br>
<input type="submit" value="Calcular" onclick="calcular()">
</form>
<table id="tablaDatos" name="tablaDatos" style="width:100%" style="text-align:center" align="center" border="1">
<tr>
<td>Numero cuota</td>
<td>Fecha emision</td>
<td>Saldo pendiente</td>
<td>Importe cuota</td>
<td>Amortizacion</td>
<td>Suma Amortizacion</td>
<td>Interes</td>
<td>Suma Interes</td>
<td>% Interes</td>
</tr>
</table>

Your button is submitting the form and is refreshing the page. Change your button from type submit to type button.
<input type="button" value="Calcular" onclick="calcular()">