I have a function foo which makes an Ajax request. How can I return the response from foo?   I tried returning the value from the success callback as well as assigning the response to a local variable inside the function and returning that one, but...

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is tha...

I have a constructor function which registers an event handler:    function MyConstructor(data, transport) {     this.data = data;     transport.on('data', function () {         alert(this.data);     }); }  // Mock transport object var tran...

Given the following examples, why is outerScopeVar undefined in all cases?  var outerScopeVar;  var img = document.createElement('img'); img.onload = function() {     outerScopeVar = this.width; }; img.src = 'lolcat.png'; alert(oute...

I have a nested data structure containing objects and arrays. How can I extract the information, i.e. access a specific or multiple values (or keys)?  For example:  var data = {     code: 42,     items: [{         id: 1,         name: 'foo'...

What are the possible reasons for document.getElementById, $("#id") or any other DOM method / jQuery selector not finding the elements?  Example problems include:   jQuery silently failing to bind an event handler jQuery "getter" me...

I have this code:  <script type="text/javascript">     var foo = 'bar';     <?php         file_put_contents('foo.txt', ' + foo + ');     ?>      var baz = <?php echo 42; ?>;     alert(baz); </scr...

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen the Scheme example given on Wikipedia,...

Is there a plugin-less way of retrieving query string values via jQuery (or without)?   If so, how? If not, is there a plugin which can do so?...

I have noticed that there doesn't appear to be a clear explanation of what the this keyword is and how it is correctly (and incorrectly) used in JavaScript on the Stack Overflow site.  I have witnessed some very strange behaviour with it and ha...