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JQuery - Every click on table changes the cell width

I'm having some weird issue with widths of table cells. All I try to do, is to get the width of the table cell using .width() function, then set that width on the same cell in width attribute:
$table.find('tr:first td').each(function () {
var actualWidth = $(this).width();
$(this).attr("width", actualWidth);
});
Every time I do that, it gets a different width for some cells (Usually reduces one and increase another).
I saw a similar question from 2012: jQuery width() returning incorrect values on table cells
But it's quite old and the accepted answer doesn't seem to work.
fiddle: https://jsfiddle.net/awolf/40pj1b2u/
Any help will be appreciated.

I think there are two problems in one. All related to the table-cell display.
The use of border attribute (border="1") in the
<table> probably messes up the width value when read. Probably the same when setting attr('width') value. In order to match the closest real value, you can use innerWidth() as #Adam P suggested.
Table cells width depends on the full available table width. In your jsfiddle sample, when expanding the table zone, cells' width are increasing. So, from each cell Width, you can compute the global table width, and apply it.
See this https://jsfiddle.net/piiantom/72dvm0v4/, taken from yours, with JS adjustments.
Table border can be changed, the JS still works

I would consider this a bug.
My interpretation:
When reading the width, it gets the content-width.
When setting it, the box gets rendered and then the border set (taking 1px from content each time).
Same with .attr(), .prop(), and .width().
Have a look at box-sizing, .innerWidth() and .outerWidth()!

Any way to change the width of an element in real time?

So Im trying to change the width of a specific element in real time. Meaning that as you scale the browser window, the element changes width along with it.
Now, the way im calculating this width is by using another element as a reference point. So i just basically copy the reference element's width and apply it to my own element. However the problem is that this is only applied after every page refresh instead of a real time change.
Im using the following jquery code:
$("#lists ul").css("width", $("#lists").width());
As you can see, the code is pretty simple. #lists ul is the elements whose width I am attempting to change and #lists is the reference element. My question is, is there a way to achieve this effect? or should I use a different approach? thanks for the help!

No need to use JavaScript to adjust widths. This should be all you need:
#lists ul { width: 100%; }

What you're trying to do sounds crazy. As others have pointed out, using a percentage in CSS is probably much smarter.
If you insist on doing it this way though... I'm guessing your event is firing within $(document).ready(). Instead, try this.
$(window).resize(function(){
$("#lists ul").css("width", $("#lists").width());
});

You can use a combination of JavaScript and CSS. I don't know what your specific needs are, but you can easily set the width of an object like this:
var element=document.getElementById("my_element");
element.style.width=10+"px";// Simple as that.
If you just want to scale your element based on its parent element's size, this is best done with CSS percent width and height.
CSS:
#my_element{
width:20%;
}
Then CSS takes care of all your scaling needs whenever the parent element is resized.
CSS by itself may not look like what you want it to be, but if you make sure to define all applicable CSS properties of your element (like margin, padding, border, etc...) and then bolster the layout with JavaScript, you can do quite a bit.

Saving off an element's CSS and reapply later

Is it possible to save off all CSS that is 'currently' applied to an element, then later reapply it? I am working on a sticking table header, and when I i change position:fixed it loses all the applied styles. I currently save off the column widths and reapply to the table header with:
$('#tableHeader').css({
position:'fixed',
width:$('#tablePanel').width(),
top:$('#top').height(),
});
$('.column1Value').width(col1Width);
$('#col1').width(col1Width);
$('.column2Value').width(col2Width);
$('#col2').width(col2Width);
$('.column3Value').width(col3Width);
$('#col3').width(col3Width);
$('.column4Value').width(col4Width);
$('#col4').width(col4Width);
$('.column5Value').width(col5Width);
$('#col5').width(col5Width);
$('.column6Value').width(col6Width);
$('#col6').width(col6Width);
$('.column7Value').width(col7Width);
$('#col7').width(col7Width);
This make the columns the correct size and line up closely, but there is extra padding or margin being applied from somewhere I can't completely figure out (bootstrap probably), and this makes the headers and columns not line up. I was hoping for something like:
var savedCSS = $('#table').css(); and retrieve it like $('#table').css(savedCSS)

You could save off the individual styles that you are interested in one by one and then re-apply them later using the jQuery("selector").css("styleName") method that you alluded to, but I don't think there's an easy way to do them all at once. It's not impossible, but wouldn't be very efficient and probably wouldn't actually give you the result you want, once the element is in its new position.
After the discussion, we found that the sizing issue wasn't really due to the styles, but due to the element that the width was being calculated from.
When the element is positioned normally in the page-flow, it uses its most recent positioned parent's width and then takes off margin to find the width of the child content.
When the element is removed from the page flow, its width is then independent of the parent. So to get the two to match up, record the parent's width rather than the element itself and set the width to match the parent, instead of trying to maintain the element's width.

Getting a div's "scrollWidth" when it has an absolute positioned child-div

I have a problem getting the width of a div's content (of the content, not the div itself).
The usual approach would be Javascript's scrollWidth property, I think.
The problem: within this div, another div is positioned absolute and has a negative right value (-350px). I can't change this (it's a menu, sliding in when you click a button, overlapping other elements. It needs to be positioned like that).
The scrollWidth returns the width of the outer div's content PLUS the negative right-value (in Chrome, didn't test other browsers).
Here's a short example:
/* ... */
http://jsfiddle.net/R4Cs5/12/
But I need the content's width that is accessible by scrollbars.
Any ideas?
Please use Jquery, no plain Javascript.
Thanks in advance.

I see that your jsfiddle doesn't import any jQuery library, while you wanted to use it. Anyway, with jQuery you can use .width to get an element's width see here: jsfiddle.

Dealing with scroll bars and jquery .width() method

jQuery's .width() method doesn't seem to account for scroll bars. This is problematic for me, since I'd like to set the width of some children to equal the width of their parent. I used jQuery similar to the following:
$('#contentDiv').width($('#containerDiv').width())
In this example, #contentDiv is the element I'd like to size, and I want to set it to have the width of #containerDiv, which is its parent element. My problem is that this cuts off the side of #contentDiv, as seen in this fiddle.
In my actual code, I have several elements that I'm sizing with jQuery, which all need to fit in the scrollable div, so just setting the css of #contentDiv to 100% is not an option. What's the best way of dealing with scroll bar widths of divs in jQuery?

The best solution I found while working around this solution is this:
http://chris-spittles.co.uk/?p=531
jQuery is all powerful and everything but sometimes a small dash of native JS is all you need to render pixel perfect pages... I hope you will find this solution helpful!

UPDATED:
None of the jQuery width-finding methods account for the scroll bar. In my original example, using .innerWidth(true) LOOKS like it works, but only because it returns and object, which causes width to fail and the inner contents size themselves to fit in the available space, because the example wasn't very good. However, it's possible to write a function to compute the available space in a div with a scroll bar in it, which can then be used to position the contents as you wish.
To write that function, I took advantage of the fact that, when a div is appended to a div with a scroll bar in it, it takes up the full available width (i.e. the inner width of the parent minus the width of the scroll bar).
The function looks like this:
function noScrollWidth(div){
var measureDiv = $('<div id="measureDiv">');
div.append(measureDiv);
var width = measureDiv.outerWidth();
measureDiv.remove();
return width
};
I then use this to size my content div:
$('#contentDiv').width(noScrollWidth($('#containerDiv')));
Working fiddle.

Try this:
$('#contentDiv').width($('#containerDiv')[0].clientWidth)
For more information about that solution, see this StackOverflow answer.

Another approach I'd try is setting both elements' box-sizing property to 'border-box', and see whether setting your contentDiv's width to 100% then works the way you want.
Now that fewer projects worry about crufty old browsers anymore, 'border-box' can make things easier to work with. Be sure to test multiple browsers on multiple platforms, though, because I'm not sure they all handle scrollbars the same way.