What is the output in the console when calling typeof a and typeof b outside the IIFE code with var? How does the behavior change in strict mode?

If variables are declared inside an IIFE using var, for example:

(function() {
  var a = 10;
  b = 20; // without var
})();

console.log(typeof a); // "undefined"
console.log(typeof b); // "number"

Variable a declared with var inside the function is local and inaccessible outside, so typeof a will return "undefined".

Variable b declared without var, let, or const, in non-strict mode, leads to the creation of a global variable. Therefore, typeof b will return "number".

In strict mode ('use strict';), attempting to assign a value to an undeclared variable (b = 20;) will throw a ReferenceError, and the global variable will not be created. Thus, outside the function, both variables will be inaccessible, and typeof a and typeof b will return "undefined" (or an error will be thrown before this).