Develop Reference

why wouldn't this selector work? JS

I have a class name active
and in js I have something like this
var selectClass = active;
var a = $("'." + selectCLass + "'");
a.on('click', function(){})
When I do this, it would keep on giving me errors.
What am I missing here?

Generated selector string has errors... make it like
var a = $("." + selectCLass);

How to select an item by attribute without jquery?

I need select element like this: $('[data-key=' + objectId + ']'), but i need select this without jquery, using document.querySelector or something else on pure JS.

You can do it with document.querySelectorAll('[data-key=' + objectId + ']') and loop through all results
var allKeys = document.querySelectorAll('[data-key=' + objectId + ']');
[].forEach.call(allKeys, function(elem){
console.log(elem); //Do your stuff with each element
});

You can try this
<p data-test="testquery">
document.querySelectorAll('[data-test]')

Javascript to get the div info

I have 4 <div> tag and <a> tag for each <div> tags.
In each and every div tag i have inserted 2 span tag and a a tag.
When the a tag is clicked i need to get the product name and the price of that div
Here is the demo http://jsfiddle.net/8VCWU/
I get the below warning message when i use the codes in the answer ...

Try this:
$(".get").click(function(e) {
e.preventDefault();
var $parent = $(this).closest(".item");
var itemName = $(".postname", $parent).text();
var itemPrice = $(".price", $parent).text();
alert(itemName + " / " + itemPrice);
});
Example fiddle
Note that you had a lot of repeated id attributes which is invalid code and will cause you problems. I've converted the #item elements and their children to use classes instead.

jQuery
$(".get").click(function(event){
event.preventDefault(); /*To Prevent the anchors to take the browser to a new URL */
var item = $(this).parent().find('#postname').text();
var price = $(this).parent().find('#price').text();
var result = item + " " + price;
alert(result)
});
DEMO
A Quick Note about id:
The id attribute specifies a unique id for an HTML element (the value must be unique within the HTML document).
A unique identifier so that you can identify the element with. You can use this as a parameter to getElementById() and other DOM functions and to reference the element in style sheets.

solution is below
use the blow code and try it
<a data-role="link" href="javascript:linkHandler('<%= obj.productname %>', '<%= obj.price %>')" class="get" >Add <a>
function linkHandler(name, price)
{
alert(name);
alert(price);
var name = name;
var price = price;
var cartItem = new item(name, parseFloat(price));
// check duplicate
var match = ko.utils.arrayFirst(viewModel.cartItems(), function(item){ return item.name == name; });
if(match){
match.qty(match.qty() + 1);
} else {
viewModel.cartItems.push(cartItem);
var rowCount = document.getElementById("cartcontent1").getElementsByTagName("TR").length;
document.getElementById("Totala").innerHTML = rowCount;
}
}

with jQuery
​$('a.get').on('click',function(){
var parent = $(this).parent();
var name = $(parent+' #postname').text();
var price = $(parent+' #price').text();
});​​​​​​​​

Or again:
$('a').click(function(e){
e.preventDefault();
var $price = $(this).siblings('#price').text();
var $postname = $(this).siblings('#postname').text();
alert($price);
alert($postname);
});

Try
function getPrice(currentClickObject)
{
var priceSpan = $(currentClickObject).parent("div:first").children("#price");
alert($(priceSpan).html());
}
and add to your a tag:
...

I'd suggest to use classed instead of id if you have more than one in your code.
The function you're looking for is siblings() http://api.jquery.com/siblings/
Here's your updated fiddle:
http://jsfiddle.net/8VCWU/14/

Hi I cleaned up the HTML as mentioned using the same Id more than once is a problem.
Using jQuery and the markup I provided the solution is trivial.
Make a note of the CSS on the below fiddle
http://jsfiddle.net/8VCWU/27/
$(document).ready(function(){
$("#itmLst a.get").click(function(){
var $lstItm = $(this).parents("li:first");
var pName = $lstItm.find("span.postname").html();
var price = $lstItm.find("span.price").html();
alert("Product Name: " + pName + " ; Price: " + price);
});
});

I have made some changes in your html tags and replace all repeated Ids with class, because you have repeated many ids in your html and it causes trouble so it is wrong structure. In HTML, you have to give unique id to each and every tag. it will not be conflicted with any other tag.
Here i have done complete bins demo. i have also specified all alternative ways to find tag content using proper jQuery selector. the demo link is as below:
Demo: http://codebins.com/bin/4ldqp8v
jQuery
$(function() {
$("a.get").click(function() {
var itemName = $(this).parent().find(".postname").text().trim();
var itemPrice = $(this).parent().find(".price").text().trim();
//OR another Alternate
// var itemName=$(this).parents(".item").find(".postname").text().trim();
// var itemPrice=$(this).parents(".item").find(".price").text().trim();
//OR another Alternate
//var itemName=$(this).closest(".item").find(".postname").text().trim();
// var itemPrice=$(this).closest(".item").find(".price").text().trim();
//OR another Alternate
//var itemName=$(this).siblings(".postname").text().trim();
//var itemPrice=$(this).siblings(".price").text().trim();
alert(itemName + " / " + itemPrice);
});
});
Demo: http://codebins.com/bin/4ldqp8v
You can check above all alternatives by un-commenting one by one. all are working fine.

Selecting textareas within div tags

feel like im coming here way too often to ask questions but yet again I am stuck. I am attempting to select a textarea and allow myself to edit the text in another textarea, which works fine using textboxs but not with textareas. Every time I click on the div container I am getting an undefined result when looking for the textarea. Below is the code.
jQuery
$(".textAreaContainer").live('click','div', function(){
var divID = this.id;
if ( divID !== "" ){
var lastChar = divID.substr(divID.length - 1);
var t = $('#' + divID ).find(':input');
alert(t.attr('id'));
t = t.clone(false);
t.attr('data-related-field-id', t.attr('id'));
t.attr('id', t.attr('id') + '_Add');
t.attr('data-add-field', 'true');
var text = document.getElementById(divID).innerHTML;
//var textboxId = $('div.textAreaContainer').find('input[type="textArea"]')[lastChar].id;
$('div#placeholder input[type="button"]').hide();
var text = "<p>Please fill out what " + t.attr('id') +" Textarea shall contain</p>";
if ( $('#' + t.attr('id')).length == 0 ) {
$('div#placeholder').html(t);
$('div#placeholder').prepend(text);
}
}
else{
}
});
t.attr('id') should be returning textbox1(or similar) but instead just returns undefined.
I have tried .find(':textarea'),.find('textarea'),.find(text,textArea),.find(':input') and quite a few others that I have found through google but all of them return undefined and I have no idea why. A demo can be found here, http://jsfiddle.net/xYwaw/. Thanks in advance for any help guys, it is appreciated.
EDIT: Below is the code for a very similar example I am using. This does what I want to do but with textboxs instead of textareas.
$('#textAdd').live('click',function() {
var newdiv = document.createElement('div');
newdiv.innerHTML = "Textbox " + textBoxCounter + " <br><div id='container" + counter + "' class='container'><li><input type='text' id='textBox" + textBoxCounter +"' name='textBox" + textBoxCounter + "'></li></div></br>";
document.getElementById("identifier").appendChild(newdiv);
textBoxCounter++
counter++;
});
$(".container").live('click','div', function(){
var divID = this.id;
if ( divID !== "" ){
var lastChar = divID.substr(divID.length - 1);
var t = $('#' + divID).find('input');
alert(divID);
t = t.clone(false);
t.attr('data-related-field-id', t.attr('id'));
alert(t.attr('id'));
t.attr('id', t.attr('id') + '_Add');
t.attr('data-add-field', 'true');
var text = document.getElementById(divID).innerHTML;
// var textboxId = $('div.container').find('input[type="text"]')[lastChar].id;
$('div#placeholder input[type="button"]').hide();
var text = "<p>Please fill out what " + t.attr('id') +" textbox shall contain</p>";
if ( $('#' + t.attr('id')).length == 0 ) {
$('div#placeholder').html(t);
$('div#placeholder').prepend(text);
}
}
else{
}
});

First up remove the second parameter, 'div', from the first line:
$(".textAreaContainer").live('click','div', function(){
...to make it:
$(".textAreaContainer").live('click', function(){
Then change:
var t = $('#' + divID ).find(':input');
...to:
var t = $(this).find(':input');
Because you already know that this is the container so there's no need to select it again by id. Also the id attributes that you're assigning to your textarea containers have a space in them, which is invalid and results in your original code trying to select the element with '#textAreaContainer 0' which actually looks for a 0 tag that is a descendant of #textAreaContainer. So fixing the code that creates the elements to remove that space in the id is both a good idea in general and an alternative way of fixing this problem.

Adding .val() without variable

I'm trying to get the value of an input, but I can't have this:
$('#inputID').val();
Inside a seperate variable.
I have the following code:
var click = "$('#highlight"+n+"').replaceWith('<span id="+id+ " style="+c+">" + $("#input" + n + "").val() + "</span>');$('#black"+n+"').hide();$('#replace_box"+n+"').remove();";
This variable is not receiving the value of the input.
Can you explain to me why the following will not work?
$('#highlight"+n+"').replaceWith('<span id="+id+ " style="+c+">" + $("#input" + n + `"").val() + "</span>');`
And can I please get a solution. Cheers.

I try some mind reading but this code won't work because you have wrong quotes:
$("#highlight"+n).replaceWith("<span id="+id+" style="+c+">"+$("#input" + n).val() +"</span>");
in any case this code would be better:
var span = $('<span />', {id: id, style: c});
span.html($("#input" + n).val());
$("#highlight"+n).replaceWith(span);