Closures in Javascript

A closure is the combination of a function and the scope object in which it was created. Closures let you save state

An example

function ageRelaxation(a) {
  return function(b) {
    return a + b;
  };
}
var boy2 = ageRelaxation(2);
var girl5 = ageRelaxation(5);
boy2(18);  // This  results 20 
girl5(20); // This  results 25