Develop Reference

Jquery multiply and add span and dropdown values

I am trying to compute the total price of items in a cart in Javascript. This is by multiplying the quantity by the unit price and then getting the grand total.
The cart is populated by a PHP while loop so I am using class names.
The quantity field is a dropdown/select and the price field is a span.
function sum() {
var sum = 0;
var q = 0;
var s = 0;
$('.itPrice,.qtys').each(function() {
q = $('.qtys').text() || 0; //quantity
s = $('.itPrice').text() || 0; //unit price
sum = sum + (q * s);
});
//display total
$("#sumT").text(sum);
}
<!-- inside PHP while loop -->
<label>Price: </label>
<span class="itPrice"><b>'.$row["price"].'</b></span>
<label>Quantity: </label>
<Select id="qty" name="qty" class="qtys">
<option value="1" selected>1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</Select>
<span id="sumT" name="sumT">*sum goes here*</span>
The output is NaN (Not a Number). Where am I going wrong? There is also a problem with the HTML select, it's not picking the selected option, only working with option '1'.

You can select both related elements, as two collections of object, an iterate one collection (while using the array index to refer to the other); that way you can get the quantity and the price.
To get a select selected element, use jquery val() function instead of text();
As a side note, you should not use duplicate id's or names for inputs in yout html. If you want an input with the same name, you can use qty[] for example.
function sum() {
var sum = 0, // Total sum
it = $('.itPrice'), // All the .itPrice elements
qty = $('.qtys'); // All the .qtys elements
// For each .itPrice element
it.each(function(i, e) {
var current = $(this), // Gets the current .itPrice element
related = $(qty[i]); // Get the related .qtys element, by array index
// Sum
sum += Number(current.find('b').text()) * related.val();
});
// return total
return sum;
}
$('#calc').click(function() {
console.log(sum());
});
console.log(sum());
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label>Price: </label>
<span class="itPrice"><b>100</b></span>
<label>Quantity: </label>
<Select id="qty" name="qty" class="qtys">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</Select>
<br>
<br>
<label>Price: </label>
<span class="itPrice"><b>200</b></span>
<label>Quantity: </label>
<Select id="qty" name="qty" class="qtys">
<option value="1" selected>1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4" selected>4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</Select>
<br>
<br>
<a id="calc" href="javascript:;">Get total</a>

How to manipulate loops with input?

i got a for loop and i would like to manipulate the counter i with a input on screen. Below i can select from 1 to 10 and i want this selection to get replaced by the counter in the loop. That means when i choose 2, then i should be 2. I started with the code below, but document.getElementById('options').innerHTML = "i"; seems to be the wrong code to manipulate. Thanks so much for your help!
<select id="options" size="1">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</select>
for (i=0, i<someArray; i++){
do somethingWith[i];}
document.getElementById('options').innerHTML = "i";

You need to get the value of the select element and assign that to i.
var i = document.querySelector('#options').value;
for(i < someArray; i++){
//code
}

Add this to HTML
<select onChange="doWork(this)">
In Js
function doWork(obj){
obj.innerHTML = obj.value
}

If want to do some thing on selection, use onchange method with select to trigger a function every time you are selecting an option.
<select id="options" size="1" onchange="myFunction()">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</select>
<p id="demo"></p>
<script>
function myFunction() {
var selectedValue = document.getElementById("options").value;
var somethingWith = [];
for (i=0; i < selectedValue; i++){
somethingWith.push(i);
}
document.getElementById('demo').innerHTML = somethingWith;
}
</script>
But if you only want to dynamically select an option in select tag, this might help
Select your favorite fruit:
<select id="mySelect">
<option value="apple">Apple</option>
<option value="orange">Orange</option>
<option value="pineapple">Pineapple</option>
<option value="banana">Banana</option>
</select>
<button type="button" onclick="myFunction()">banana</button>
<script>
function myFunction() {
document.getElementById("mySelect").value = "banana";
}
</script>

How to store multiple values from multiple select field using javascript?

I am having trouble to store all the selected options as a list, my code only sotres the first selected option and ignores the rest. How can I solve this problems?
<label for="itemlist">Items</label>
<br>
<select id="itemlist" name="itemlist" multiple="multiple" required>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
</select>
<script type="text/javascript">
$(function() {
$('#itemlist').change(function() {
console.log($(this).val());
}).multipleSelect({
width: '100%'
});
});
</script>

Gus,
As you are using it jQuery already $('selector').val(), this will retreive (comma separated) all values selected on the select tag.
Here is an example I've wrote for you using the .on('click', function).
FIDDLE
Hope this helps!

textboxes on dropsown select

I am beginner with jQuery. I want to use drop down in my page. Depending upon the selection of drop down value, no of text boxes should appear in page. Suppose I selected 8 than 8 text boxes appear and if then I select 4 than rest four should be removed. Please give me idea how to do it using jQuery.

jQuery('#select').change(function() {
var num = jQuery(this).val();
jQuery('.textboxes').remove();
for(i=0;i<num;i++)
{
jQuery("<input type='text' class='textboxes' />").appendTo("body");
}
});
Here select is the id of the selectbox.

Rahul you are asking for an idea so here it is. Using jQuery you can find the value of a drop down or select element and use that value to simply append new text boxes. I would suggest not to create elements but insert html for those elements.
<script src="http://code.jquery.com/jquery-latest.js"></script>
<select name="select" id="select">
<option value="0">0</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</select>
<div id="textbox-container"></div>
<script>
$(document).ready(function() {
$('#select').change(function() {
var num = $('#select').val();
$('.textboxes').remove();
var textBoxesStr = '';
for (i = 0; i < num; i++) {
textBoxesStr = textBoxesStr + "<input type='text' class='textboxes' />";
}
$("#textbox-container").append(textBoxesStr);
});
});
</script>
Code given above works for me.

<html>
<head>
<title>Dynamic Form</title>
<script language="javascript">
function changeIt()
{
document.getElementById("my_div").innerHTML="";
var num=document.getElementById("select").options[document.getElementById("select").selectedIndex].value;
for(i=0;i<num;i++)
{
my_div.innerHTML = my_div.innerHTML +"<br><input type='text' name='mytext'+ i>"
}
}
</script>
</head>
<body>
<form name="form" action="post" method="">
<select name="select" id="select">
<option value="0">0</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</select>
<input type="button" value="test" onclick="changeIt()">
<div id="my_div"></div>
</form>
</body>
</html>

Selecting value of <select> tag in javascript. problem

I have an external Javascript file and i am trying to alert the value of select tag.
My <select> code looks like this:
<select id="vote">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>
<input type="button" value="vote" onclick="castvote();">
and the Javascript (which is external):
function castvote()
{
alert(document.vote.options[document.vote.selectedIndex].value);
}
But I get the error "document.vote is undefined".
Can someone help me with this.
Best
Zeeshan

If selecting by Id, you should use :
function castvote() {
var sel = document.getElementById("vote");
alert(sel.options[sel.selectedIndex].value);
}

Easy way, change your code so that your form field has a name attribute:
<select name="vote" id="vote">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>
<input type="button" value="vote" onclick="castvote();">
Better way, change your javascript so it is retreiving the select box by its ID rather than through the document object:
function castvote() {
var mySelect = document.getElementById("vote");
alert(mySelect.options[mySelect.selectedIndex].value);
}