CLOSURES

Closures

It is the combination of a function and the lexical environment within which that function was declared.

i.e, It is an inner function that has access to the outer or enclosing function’s variables. The closure has three scope chains

Own scope where variables defined between its curly brackets
Outer function’s variables
Global variables

function Welcome(name) {
  var greeting = function (message) {
    console.log(message + " " + name);
  };
  return greeting;
}
var myFunction = Welcome("John");
myFunction("Welcome "); //Output: Welcome John
myFunction("Hello Mr."); //output: Hello Mr.John

As per the above code, the inner function (i.e, greeting) has access to the variables in the outer function scope (i.e, Welcome)even after the outer function has returned.