Why is the value not assigned to the variable in case of an IIFE?

Question

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

console.log(a, b);



(function() {
    var x = y = 3;
    console.log(x, y);    
})();

These are very simple program. But I'm confused why a is undefined while b has value 3 in the output of the first example program while both x and y are having the value 3 in the second example program?

Answer 1

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

console.log(a, b);

When a IIFE is created , a function is created and is called.Here a is the local variable and variables have local scope so you cant access it outside

You havent used var in front of b so it becomes the global variable and hence is reflected outside the function scope too