scope.md

JavaScript Scope

Lets start with a really intersting question:

(function () {
  var a = b = 3;
})();

console.log(b); // 3
console.log(a); // Uncaught ReferenceError: a is not defined

/*https://stackoverflow.com/a/27329475/12666332
lookup(rhs,lfs)
b = 3;
var a = b;
*/

What is the meaning of Scope?

A: Scope determines the accessibility (visibility) of variables. e.g.Each function creates a new scope. So, Variables defined inside a function are not accessible (visible) from outside the function.W3schools