Python variables are scoped to the innermost function, class, or module in which they’re assigned. Control blocks like if and while blocks don’t count, so a variable assigned inside an if is still scoped to a function, class, or module. (Implicit functions defined by a generator expression or list/set/dict comprehension do count, as do lambda … Read more
Introduction It represents the scope (the lifetime) of the bean. This is easier to understand if you are familiar with “under the covers” working of a basic servlet web application: How do servlets work? Instantiation, sessions, shared variables and multithreading. @Request/View/Flow/Session/ApplicationScoped A @RequestScoped bean lives as long as a single HTTP request-response cycle (note that … Read more
Edit: The issue addressed in this answer have been resolved in angular.js version 1.2.7. $broadcast now avoids bubbling over unregistered scopes and runs just as fast as $emit. So, now you can: use $broadcast from the $rootScope listen using $on from the local $scope that needs to know about the event Original Answer Below I … Read more
Actually, a concise rule for Python Scope resolution, from Learning Python, 3rd. Ed.. (These rules are specific to variable names, not attributes. If you reference it without a period, these rules apply.) LEGB Rule Local — Names assigned in any way within a function (def or lambda), and not declared global in that function Enclosing-function … Read more
Editor’s Note: All functions in JavaScript are closures as explained in this post. However we are only interested in identifying a subset of these functions which are interesting from a theoretical point of view. Henceforth any reference to the word closure will refer to this subset of functions unless otherwise stated. A simple explanation for … Read more
const is like let, it is a LexicalDeclaration (VariableStatement, Declaration) used to define an identifier in your block. You are trying to mix this with the default keyword, which expects a HoistableDeclaration, ClassDeclaration or AssignmentExpression to follow it. Therefore it is a SyntaxError. If you want to const something you need to provide the identifier … Read more
As the others have said, you can use var at global scope (outside of all functions and modules) to declare a global variable: <script> var yourGlobalVariable; function foo() { // … } </script> (Note that that’s only true at global scope. If that code were in a module — <script type=”module”>…</script> — it wouldn’t be at global … Read more
It’s usually to namespace (see later) and control the visibility of member functions and/or variables. Think of it like an object definition. The technical name for it is an Immediately Invoked Function Expression (IIFE). jQuery plugins are usually written like this. In Javascript, you can nest functions. So, the following is legal: function outerFunction() { … Read more
Break the chain When you need to access the intermediate values in your chain, you should split your chain apart in those single pieces that you need. Instead of attaching one callback and somehow trying to use its parameter multiple times, attach multiple callbacks to the same promise – wherever you need the result value. … Read more
The compiler declares the variable in a way that makes it highly prone to an error that is often difficult to find and debug, while producing no perceivable benefits. Your criticism is entirely justified. I discuss this problem in detail here: Closing over the loop variable considered harmful Is there something you can do with … Read more