Tutorial by Examples: r

Allowing user credentials or the user's session to be sent with a CORS request allows the server to persist user data across CORS requests. This is useful if the server needs to check if the user is logged in before providing data (for example, only performing an action if a user is logged in - this...

A basic CORS request is allowed to use one of only two methods: GET POST and only a few select headers. POST CORS requests can additionally choose from only three content types. To avoid this issue, requests that wish to use other methods, headers, or content types must first issue a preflig...

When a server receives a preflight request, it must check if it supports the requested method and headers, and send back a response that indicates its ability to support the request, as well as any other permitted data (such as credentials). These are indicated in access-control Allow headers. The ...

var app = {}; app.signUp = function(){ app.userName = $('#userName').val(); app.password = $('#password').val(); app.email = $('#form-email').val(); app.phoneNumber = $('#form-phone').val(); app.emailRegex = ...

Mostly you will use "normal variables": set(VAR TRUE) set(VAR "main.cpp") set(VAR1 ${VAR2}) But CMake does also know global "cached variables" (persisted in CMakeCache.txt). And if normal and cached variables of the same name exist in the current scope, normal var...

The scope outside of any function or class is the global scope. When a PHP script includes another (using include or require) the scope remains the same. If a script is included outside of any function or class, it's global variables are included in the same global scope, but if a script is include...

The most important use of ranges is to express a sequence Syntax: (begin..end) => this construct will include end value (begin...end) => this construct will exclude end value or Range.new(begin,end,exclude_end) => exclude_end is by default false Most important end value must be gr...

A Regexp can be created in three different ways in Ruby. using slashes: / / using %r{} using Regex.new #The following forms are equivalent regexp_slash = /hello/ regexp_bracket = %r{hello} regexp_new = Regexp.new('hello') string_to_match = "hello world!" #All of th...

Sometimes you want to convert your enum to a String, there are two ways to do that. Assume we have: public enum Fruit { APPLE, ORANGE, STRAWBERRY, BANANA, LEMON, GRAPE_FRUIT; } So how do we convert something like Fruit.APPLE to "APPLE"? Convert using name() name() is an inte...

Superglobal variables are defined by PHP and can always be used from anywhere without the global keyword. <?php function getPostValue($key, $default = NULL) { // $_POST is a superglobal and can be used without // having to specify 'global $_POST;' if (isset($_POST[$key])) { ...

Static class properties that are defined with the public visibility are functionally the same as global variables. They can be accessed from anywhere the class is defined. class SomeClass { public static int $counter = 0; } // The static $counter variable can be read/written from anywhere...

When we want to count the number of items in an iterable, that meet some condition, we can use comprehension to produce an idiomatic syntax: # Count the numbers in `range(1000)` that are even and contain the digit `9`: print (sum( 1 for x in range(1000) if x % 2 == 0 and '9' in str...

let someValue : String = "Something the user entered" let text = NSMutableAttributedString(string: "The value is: ") text.appendAttributedString(NSAttributedString(string: someValue, attributes: [NSFontAttributeName:UIFont.boldSystemFontOfSize(UIFont.systemFontSize())])) ...

Equals is declared in the Object class itself. public virtual bool Equals(Object obj); By default, Equals has the following behavior: If the instance is a reference type, then Equals will return true only if the references are the same. If the instance is a value type, then Equals will...

Like any other java program, every swing program starts with a main method. The main method is initiated by the main thread. However, Swing components need to be created and updated on the event dispatch thread (or short: EDT). To illustrate the dynamic between the main thread and the EDT take a loo...

In Java, we can convert between integer values and floating-point values. Also, since every character corresponds to a number in the Unicode encoding, char types can be converted to and from the integer and floating-point types. boolean is the only primitive datatype that cannot be converted to or f...

defmodule Processes do def receiver do receive do {:ok, val} -> IO.puts "Received Value: #{val}" _ -> IO.puts "Received something else" end end end iex(1)> pid = spawn(Processes, ...

Recursion can be used to receive multiple messages defmodule Processes do def receiver do receive do {:ok, val} -> IO.puts "Received Value: #{val}" _ -> IO.puts "Received something else" end...

Detailed instructions on getting jvm set up or installed.

For a function or subroutine to be useful it has to be referenced. A subroutine is referenced in a call statement call sub(...) and a function within an expression. Unlike in many other languages, an expression does not form a complete statement, so a function reference is often seen in an ass...