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using foreach of class inside another class

I use foreach for instances of class ( let say class1 ) inside prototype method of another class(class2), anyway it works well but when I try to use (this) to refer to some vales of class1 it doesn't work, any help?

Step 1: Look how to post questions on SO.
Step 2: If you program JS you need to know how this works, this case is not the real issue, the issue is you don't. Plenty of tutorials to google on that, I would recommend it since understanding how this works in JS is essential.
Depending on your actual code this could be enough to get you going:
The bind() method creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called.
So in a place where you call your function try using this beforehand:
var _this = this;
Then call your function:
whateverobj.myfunction().bind(_this)

Prototype function creating elements and using inheritance invoked on load instead of on click

I apologize if the following are stupid questions, this is my first time trying something with OO JS which goes beyond the very basic tutorials out there.
If I get to understand the following questions, it would constitute something like a person breakthrough:-)
Basically, I want to create an element- a div with a background pic- on click and append it to the button.(Later on i want to create an additional button which will replace the above pic with another one).
The pictures are stored in an Array.
If i run this with the commented out lines 37-57, it all works, but i do not want to write that function every time to create the next element.
So I have created the function object "Nation"(lines 4 to 30) and want to pass 2 arguments on call, "land"(name of nation) and "imageIndex"(index of picture in the array).
Here is where the problems start. I want to call new Nation on click(line, but it is executed straight on page load instead. How to fix that?
And I have not passed the second argument now, as I could not figure out how to do it, so I just used line 13 to set the BG pic. But the goal would be to set the BG pic by passing a second argument to the function.
var croats = new Nation("croatia");
document.getElementById("newDom")
.addEventListener("click", croats.create("croatia"));
That is the event handling and the code is here:
http://codepen.io/damianocel/pen/gPggLB
Thank you very much.

You should simply pass a function as 2nd argument of the addEventListener:
document.getElementById("newDom").addEventListener("click", function () {
croats.create("croatia")
});
See for example: https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#Example
As your code is currently set, it executes croats.create() when attaching the listener, instead of storing a reference to a function (called "listener" or "callback") to be executed when the event occurs.
Updated CodePen: http://codepen.io/anon/pen/KVqgdP

JavaScript: how to pass object value from one function to another

I am using code lines like the following in order to fetch data from an intranet website:
util.setProp(obj, "firstNameOld", $(msg).find('#fname_a').text());
Now I have another function in the same file where I want to use the above again, resp. the value of that object - currently I am hard-coding this ('Test') for test purposes:
util.setProp(obj, "firstNameNew", 'Test');
How can I pass the value from the firstNameOld object in one function to the firstNameNew object in another function ? If a solution with global variables is better here than this would work as well.
Many thanks for any help with this, Tim.

I've never used the framework that includes util But I imagine that if there is a setProp() then there has to be a getProp() or something similar.
If so, you could do something like
util.setProp(obj, "firstNameNew", util.getProp(obj, "firstNameOld"));
This also relies on the assumption that you want to copy from two properties in the same object.
If not, then pass the desired source object in the getProp() call.

My guess is that functions (or properties) are called "firstNameOld" and "firstNameNew", so the first time you get it from selector, second time you want to do the same.
Try to use the local variable like that:
var text = $(msg).find('#fname_a').text();
//
util.setProp(obj, "firstNameOld", text);
//
util.setProp(obj, "firstNameNew", text);

Does Javascript temporary object need reference variable and/or closures?

I need short messages disappearing after preset time. Please see the fiddle here: http://jsfiddle.net/X88F9/1/.
It works well, what I am not sure about is the reference for each created object:
function addObject() {
new SomeObj(Math.random() * 1000 + 300);
}
it is not stored in any variable, can I just leave it as it is ? Or do I need to push them in some array ?
I also found this recommendation to put all in closures: https://stackoverflow.com/a/10246262/2969375, but not sure if necessary in my case and if yes, then how.

My answer to the question is: Javascript does not need a reference to the object to work, as proofed by your fiddle. So the question is more about if you need a reference to the object, to do other stuff with it later on. If you, for instance, would like to give the user the ability to click the temporarily display message and stop it from disappearing, than you can put all that code in a closure and do not need a reference, too. But if you would like to display the very same object again after it was removed from the DOM, than you need to store it in an array, other object, or variable, depending on your needs and ways to find it in a list.

Passing values from Greasemonkey sandbox into anonymous functions

This is my first question, probably very silly indeed :)
I have a selection of values in an array, returned from GM_listValues().
As I loop over the collection, I want to dynamically create buttons that call a function to delete the stored value, and reload the page.
deleteB.addEventListener("click", function() {deleteTrip(names[i]);pageSelect();}, false);
Above is the line I am using to attach the event to the button (deleteB). However, when I press the button, javascript tries to access the array of listValues (names) with the count variable (i). Naturally, this will not exist, as the loop is now done, and names is not global anyway.
What I want to know is if there is a way to copy the string value of names[i] while I am creating the function in the button, so as to not need a reference to names[i] in the code.
I know this is probably a really simple answer, but its got me stumped, this is some of my first work with javascript.
Thanks in advance.

Use a closure to remember the value;
function createDeleteFunc(name) {
return function(){deleteTrip(name);pageSelect();}
}
for() {
...
deleteB.addEventListener("click", createDeleteFunc(names[i]), false);
...
}

The problem is that all functions you create reference the same i variable. When they are called, they try to delete names[i], but i is now equal to names.length so it doesn't work.
The solution is to make a separate reference to names[i] for each function. This is usually done with a closure (à-la Paul's answer)