Closure of JavaScript and C#.

A closure is a function that is evaluated in an environment containing one or more bound variables.

JavaScript.

function closure(init) {
  var cnt = init;

  return function() {
    return ++cnt;
  }
}

var r = closure(10);

alert(r());
alert(r());
alert(r());

C#.

Func<int, Func<int>> closure = init =>
    {
       int cnt = init;
       return () => ++cnt;
    };

var r = closure(10);

Console.WriteLine(r());
Console.WriteLine(r());
Console.WriteLine(r());

Output.

11
12
13