Develop Reference

Javascript for counting the values of text input fields

I am trying to create a hotel booking form with an increment counter which I have already setup. Its got 3 input fields and at the end there is a "group total" text input field. I need to ask if anyone could help me with the JS in order to counter the number of individuals in the total group box for when they incrementally add people in the 3 increment counters?
My code is as follows:
function increase() {
var a = 1;
var textbox = document.getElementById("text");
textbox.value++;
}
function decrease() {
var textBox = document.getElementById("text");
textBox.value--;
}
function increase2() {
var a = 1;
var textbox2 = document.getElementById("text2");
textbox2.value++;
}
function decrease2() {
var textBox2 = document.getElementById("text2");
textBox2.value--;
}
function increase3() {
var a = 1;
var textbox3 = document.getElementById("text3");
textbox3.value++;
}
function decrease3() {
var textBox3 = document.getElementById("text3");
textBox3.value--;
}
<h4>Please select the number of people who will be in each room</h4>
<div class="cart-plus-minus">
<button type="button" onclick="decrease()">-</button>
<input type="text" id="text" value="1" min="1" data-max="2" readonly>
<button type="button" onclick="increase()">+</button>
</div>
<div class="cart-plus-minus">
<button type="button" onclick="decrease2()">-</button>
<input type="text" id="text2" value="1" min="1" max="2" readonly>
<button type="button" onclick="increase2()">+</button>
</div>
<div class="cart-plus-minus">
<button type="button" onclick="decrease3()">-</button>
<input type="text" id="text3" value="1" min="1" max="2" readonly>
<button type="button" onclick="increase3()">+</button>
</div>
<a href="" class="a-link">
<label> Group Total: </label>
<input id="totalPersons" type="text" placeholder="" value="">
</a>

You can simplify your code by adding this to all onclick function calls so we can know which element called the function and with that we can figure out it's parent along with the correct input element to increment. In the end we call the increaseTotal() or decreaseTotal() function to update the group total field.
Note: I'm guessing you don't want to be able to decrease a field beyond 0, so I added that constraint as an if statement in the decrease() function. I also made the totalPersons input field's value to default to 3 because all of the 3 other inputs default to 1.
Run and test:
function increase(el) {
var textbox = el.parentElement.querySelector('input');
textbox.value++;
increaseTotal();
}
function decrease(el) {
var textBox = el.parentElement.querySelector('input');
if(textBox.value > 0) { // <- if value is at least 1
textBox.value--;
decreaseTotal();
}
}
function increaseTotal() {
var textBox = document.getElementById("totalPersons");
textBox.value++;
}
function decreaseTotal() {
var textBox = document.getElementById("totalPersons");
textBox.value--;
}
<h4>Please select the number of people who will be in each room</h4>
<div class="cart-plus-minus">
<button type="button" onclick="decrease(this)">-</button>
<input type="text" id="text" value="1" min="1" data-max="2" readonly>
<button type="button" onclick="increase(this)">+</button>
</div>
<div class="cart-plus-minus">
<button type="button" onclick="decrease(this)">-</button>
<input type="text" id="text2" value="1" min="1" max="2" readonly>
<button type="button" onclick="increase(this)">+</button>
</div>
<div class="cart-plus-minus">
<button type="button" onclick="decrease(this)">-</button>
<input type="text" id="text3" value="1" min="1" max="2" readonly>
<button type="button" onclick="increase(this)">+</button>
</div>
<a href="" class="a-link">
<label> Group Total: </label>
<input id="totalPersons" type="text" placeholder="" value="3">
</a>

You could just increase/decrease the value attribute of the totalpersons element within the increase/decrease methods as well.
For example:
function increase() {
var a = 1;
var textbox = document.getElementById("text");
var totalpersons = document.getElementById("totalPersons");
textbox.value++;
totalpersons.value++;
}

Note that the values of text boxes are always strings in javascript. The parseInt() function will convert them to integers.
https://jsfiddle.net/y473L1bt/2/
function updateTotal() {
var textbox = document.getElementById("text");
var textbox2 = document.getElementById("text2");
var textbox3 = document.getElementById("text3");
var total = document.getElementById("totalPersons");
total.value = parseInt(textbox.value) +
parseInt(textbox2.value) + parseInt(textbox3.value);
}
function increase(id) {
var textbox = document.getElementById(id);
textbox.value++;
updateTotal();
}
function decrease(id) {
var textBox = document.getElementById(id);
var a = textBox.value - 1;
if (a >= 0) {
textBox.value = a;
}
updateTotal();
}

How to create a unique id from the first two fields in the form?

I created a form with three fields first_name, Last_name, city and in the fourth field, I am having an Id column which is read-only. When the user fills the first three fields in the form, before submitting it should generate an id in the fourth column but here it should use the first two alphabets that are in the fields to generate an Id
For eg. First_name = Roid, Last_name = Steve, city = California then in the fourth field it should automatically generate this id = rostca (all the first two alphabets)
How to achieve this?

Here is a JavaScript version to answer to your issue.
(function () {
populate();
})();
function populate () {
var str = "";
Array.from(document.getElementsByClassName("inputs")).forEach(function (element) {
str += element.value.substr(0, 2).toLowerCase();
});
document.getElementById("output").value = str;
}
<div>
<input type="text" class="inputs" value="Roid" oninput="populate();" />
<input type="text" class="inputs" value="Steve" oninput="populate();" />
<input type="text" class="inputs" value="California" oninput="populate();" />
<input id="output" type="text" readonly disabled />
</div>
Here is a jQuery answer to your issue.
$(function () {
populate();
$(".inputs").on("input", function() {
populate();
});
});
function populate () {
var str = "";
$(".inputs").each(function () {
str += $(this).val().substr(0, 2).toLowerCase();
});
$("#output").val(str);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div>
<input type="text" class="inputs" value="Roid" />
<input type="text" class="inputs" value="Steve" />
<input type="text" class="inputs" value="California" />
<input id="output" type="text" readonly disabled />
</div>

Check below code,
function TextChanged(){
var first_name = document.getElementById("first_name").value;
var Last_name = document.getElementById("Last_name").value;
var city = document.getElementById("city").value;
document.getElementById("id").value = first_name.substring(0, 2) +Last_name.substring(0, 2) +city.substring(0, 2);
}
<input type="text" id="first_name" onblur="TextChanged()">
<input type="text" id="Last_name" onblur="TextChanged()">
<input type="text" id="city" onblur="TextChanged()">
<input type="text" id="id" readonly>
Check here jsbin demo, https://jsbin.com/qegazab/edit?html,js,console,output

Generating random password into input with input length using Javascript

<form name="pgenerate">
<input type="text" size=18 name="output">
<input type="button" value="Generate Password" ><br />
<b>Password Length:</b> <input type="text" name="thelength" size=3 value="7">
</form>
How can i make a random password generator that will generate password inside an input you can use in you projects or systems

var keylist="abcdefghijklmnopqrstuvwxyz123456789"
var temp=''
function generatepass(plength){
temp=''
for (i=0;i<plength;i++)
temp+=keylist.charAt(Math.floor(Math.random()*keylist.length))
return temp
}
function populateform(enterlength){
document.pgenerate.output.value=generatepass(enterlength)
}
<form name="pgenerate">
<input type="text" size=18 name="output">
<input type="button" value="Generate Password" onClick="populateform(this.form.thelength.value)"><br />
<b>Password Length:</b> <input type="text" name="thelength" size=3 value="7">
</form>

No need to reinvent the wheel. Check out this library: https://www.npmjs.com/package/generate-password which does exactly what you want.

Try this pure JS solution:
function generateRandomPassword (passwordLength) {
var outputPassword = "";
var allPossibleChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
for (var i = 0; i < passwordLength; i++) {
outputPassword += allPossibleChars.charAt(Math.floor(Math.random() * allPossibleChars.length));
}
return outputPassword;
}
<form name="pgenerate">
<input type="text" size=18 id="output" name="output">
<input type="button" value="Generate Password" onclick="document.getElementById('output').value = generateRandomPassword(document.getElementById('thelength').value);"><br />
<b>Password Length:</b> <input type="text" id="thelength" name="thelength" size=3 value="7">
</form>
If you want to add more possible chars simply update allPossibleChars.

How do I use javascript or jquery to find a sum and product of values from a forms field inputs?

How do I use javascript or jquery to find a sum and product of number values that users enter into my forms fields. Thanks for your time and help.
Input 1 Value + Input 2 Value = Input A
Input A Value * .08 = Input B Value
Input A Value + Input B Value = Total Input
<form>
<input type="text" id="1" name="1">
<input type="hidden" id="2" name="2" value="33">
<input type="text" id="A" name="A">
<input type="text" id="B" name="B">
<input type="text" id="total" name="total">
<button type="button" id="button" name="button">
</form>
WHAT IVE TRIED
<script>
var $form = $('#contactForm'),
$summands = $form.find('.sum1'),
$sumDisplay = $('#itmttl');
$form.delegate('.sum1', 'change', function ()
{
var sum = 0;
$summands.each(function ()
{
var value = Number($(this).val());
if (!isNaN(value)) sum += value;
});
$sumDisplay.val(sum);
});
</script>
<script>
function multiply(one, two) {
if(one && two){
this.form.elements.tax.value = one * two;
} else {
this.style.color='blue';
}
}
</script>

Please find Fiddle link
JSFiddle
$(document).ready(function(){
$('#calculate').on('click',function(){
var v1 = $('#1').val(); // take first text box value
var v2 = $('#2').val(); // take second hidden text box value
$('#A').val(parseInt(v1)+parseInt(v2)); // set value of A
var aval = (parseInt($('#A').val()) * parseFloat(.8)); // calculate value of b
$('#B').val(aval);// set value of B
var totalval = parseInt($('#A').val()) + parseFloat(aval);
//calculate value for total
$("#total").val(totalval); // set total
})
});

I assume you want to update the fields when you lick the button? Created a snippet instead of a fiddle:
$("#button").click(function() {
$("#A").val( parseInt($("#1").val()) + parseInt($("#2").val()) );
$("#B").val(parseInt($("#A").val()) * .8);
$("#total").val( parseInt($("#A").val()) + parseInt($("#B").val()) );
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form>
<input type="text" id="1" name="1">
<input type="hidden" id="2" name="2" value="33">
<input type="text" id="A" name="A">
<input type="text" id="B" name="B">
<input type="text" id="total" name="total">
<button type="button" id="button" name="button">
</form>

2 name attributes for a field in a form

I have a script that calculates the values in each and shows the calulated values. At the end it also calculates the already calculated values from all div's
Here is the html code:
<td>
<div>
<input name="r" class="rate" type="text" maxlength="255" size="5" value />
<input name="p" class="pack" type="text" maxlength="255" size="5" value />
<span class="amount"></span>
</div>
</td>
<td>
<div>
<input name="r" class="rate" type="text" maxlength="255" size="5" value />
<input name="p" class="pack" type="text" maxlength="255" size="5" value />
<span class="amount"></span>
</div>
</td>
The problem is that I want to put all fields in a form and then submit them to a database.
However, all divs contain two input fields with name "r" and "p".
So, I am kind of stuck here because I cannot figure out how to make the names unique or how to have them passed to the DB using POST.
This is what the calculating script looks like:
<script type="text/javascript">//<![CDATA[
//any time the amount changes
$(document).ready(function() {
$('input[name=r],input[name=p]').change(function(e) {
var total = 0;
var $row = $(this).parent();
var rate = $row.find('input[name=r]').val();
var pack = $row.find('input[name=p]').val();
total = parseFloat(rate * pack);
//update the row total
$row.find('.amount').text(total);
var total_amount = 0;
$('.amount').each(function() {
//Get the value
var am= $(this).text();
console.log(am);
//if it's a number add it to the total
if (IsNumeric(am)) {
total_amount += parseFloat(am, 10);
}
});
$('.total_amount').text(total_amount);
});
});
//isNumeric function Stolen from:
//http://stackoverflow.com/questions/18082/validate-numbers-in-javascript-isnumeric
function IsNumeric(input) {
return (input - 0) == input && input.length > 0;
}
//]]>
</script>

HTML:
<input type="text" name="r[]">
<input type="text" name="p[]">
<hr>
<input type="text" name="r[]">
<input type="text" name="p[]">
<hr>
<input type="text" name="r[]">
<input type="text" name="p[]">
PHP:
for ($i = 0; $i < count($_POST['p']); $i++) {
$rate = $_POST['r'][$i];
$pack = $_POST['p'][$i];
// do something with $rate and $pack
}
Since the browser submits all inputs (even if no value has been entered) and by specification it submits them in the order they are defined in the HTML code, you can rely that the elements in the two $_POST arrays will line up and the corresponding rate and pack will be received at the same index in the respective array.