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What does a javascript object dataset attribute combined with a bitwise or and 0 do?

I came across this pen when searching for a way to make a textarea auto-expand with input: https://codepen.io/vsync/pen/frudD. The code includes the line
var minRows = elm.getAttribute('data-min-rows')|0, rows;
I do not understand what the bitwise or and 0 after getting the dataset attribute does. I tried removing them, but that breaks the code.
Also, I think that the ", rows" is a remnant from a previous version of the code as "rows" is not defined until later in the code, and I can remove that and the code still appears to work (please correct if I am missing something).

The bitwise OR and 0 serves to convert the string property into a number to work properly. This can be verified by checking the type of the variable.
Usually, the stuff after the comma is used as the result, but since it is undefined, whatever comes in front is used instead (I think).

Parsing a string returned from ckeditor using javascript string methods

I am trying to get a certain area of data out from ckeditor. In order to do that I use the following code
function get_body_html(){
var email = CKEDITOR.instances['message'].getData();
var before_body = header_to + to + to_subject + subject + subject_body;
var s_index = email.indexOf(before_body)+before_body.length;
var e_index = email.indexOf(body_footer);
return email.substring(s_index,e_index);
}
For some reason that works when I do this on page load
CKEDITOR.instances.message.setData(header_to + to + to_subject+
subject + subject_body + body_text + body_footer);
get_body_html();
it works correctly and gives me the same string that is contained in body_text.
But when I do this
body_text = get_body_html();
CKEDITOR.instances.message.setData(header_to + to + to_subject + subject +
subject_body + body_text + body_footer);
in an onclick function it gets the wrong indexs somehow. Sometimes it can't find the string and returns -1 other times it just gets a weird index that doesn't make sense. These index variations only happen when my code is changed to tackle the problem a different way. So if it is the wrong indices like -5 and 2 then those would continue to be the wrong indices until I made a code change.

There are two facts that you should know about editor.setData.
In some cases it is asynchronous (it depends on the type of editor). That's why it also accepts a callback. Therefore any code that is meant to be executed after setData() should be executed in that callback.
It never is asynchronous before editor is ready. In this period (between editor initialization and instanceReady event) it works in a different mode - it just caches the set value and on getData() it returns exactly that value.
So, as I see on page load you call synchronously setData() and getData() - your function works because you get the value you're expecting to get.
But then, when you try to getData() when editor is already ready you get the HTML parsed, fixed, processed and perhaps differently formatted by CKEditor. I guess that your indexOf() checks are not enough to handle this. You have to rethink your function - e.g. regexp can help.
What also can help is removing htmlwriter plugin, which formats HTML in a way which may make it harder for you to work with it. E.g.:
config.removePlugins = 'htmlwriter';

I was able to get it to work. So the htmlwriter was one of the problems because it must add spaces in between by HTML tags. The other issue I found is that it strips some of the semicolons out in some of the style attributes. Overall CKEditor does a lot of formatting of the source which makes it very hard to index correctly but it's pretty much a trial and error thing. I ended up using the search JavaScript method for strings which can take a regular expression but I used it the same way indexOf would be used so I don't really know if that made a difference or not.

Javascript: strip first and last \ from regExp variable

I'm cobbling together a script which maps mouse X,Y coordinates to an axis grid. The resulting variable will then be passed to CSS transform property. I'm getting all the numbers I need, but I'm stuck on the last part, which is to remove the \ around the result, which has been converted to a regular expression so as to allow for negative integers.
var resultX = RegExp(Math.round(mousePos.x/6.6) -60);
resultX = resultX.replace(/\//g,'');
The final stage (stripping the slashes) throws an error no matter how I do it. I've tried encapsulating .replace in a function, and using return, but I continue to get the same error:
TypeError: 'undefined' is not a function (evaluating
'resultX.replace(///g,'')')
I'm stuck, and haven't been able to find the solution anywhere. Perhaps the problem is that my variable isn't a true string? Or maybe someone has a suggestion for a better way to allow for negative integers.
JS fiddle:
http://jsfiddle.net/wAKnY/

Like JayC mentioned in the comments, there doesn't seem to be a reason to convert to a RegExp in the first place, so I would just recommend removing the enclosing RegExp().
However, if you require that for some reason that isn't apparent here, you can then call toString() on it to enable the replace function to behave correctly:
resultX = resultX.toString().replace(/\//g,'');

As JayC said, you don't need a regexp in the first place.
var resultX = (Math.round(mousePos.x/6.6)-60).toString;

This works:
resultX = resultX.toString().replace(/\//g, '');
resultY = resultY.toString().replace(/\//g, '');

Error in javascript function

I am using the following code
function xhi(aax)
{
var aby=document.getElementById(aax);
aby.style.bottom=(parseInt(aby.style.bottom)+(screen.height-42)/10)+'px';
if(parseInt(aby.style.bottom)<(screen.height-42))setTimeout('xhi("'+aax+'")',25);
}
When i run this code the function calls itself only two times . second time aby.style.bottom becomes Null.Why?

Check the bottom value. It might be crazy, but if the value is something like 008, 010, etc.
parseInt treats the number as octal. In order to avoid this, use :
parseInt(aby.style.bottom,10)
Why are you using bottom? I believe the best approach is the top attribute.
If everything else fails, jQuery has some nice functions to animate and to grab those style attributes.

I am not sure but try after removing from your code +'px' .

Removing comma for value with Javascript

thanks for looking my questions, I can't find the way to remove the comma with javascript. So I have problem at removing comma from page with java-script, Adding Comma for output is fine i guess, but for removing comma for value, the function is not working for me.
The source code is : http://jsfiddle.net/Q5CwM/2/
Please let me know, thanks again.

I have no idea what your code is trying to do overall, but you can fix this function that removes commas:
function checkNumeric(objName) {
var lstLetters = objName;
var lstReplace = lstLetters.replace(/\,/g,'');
}
by changing it to this:
function removeCommas(str) {
return(str.replace(/,/g,''));
}
You weren't returning the changed string from the function and I changed the name of the function and parameters to represent what it does.
str.replace returns the changed string. It does not change the string you started with so in order to do something with the result of the replacement, you have to either return that from the function or assign it to some other string. As you had it, nothing was happening with the replaced string so the function did nothing.