Variable scope and closure operations for JavaScript

Scope of the variable:

Each function defines the scope, and the function is declared internally with Var, whose scope is only useful within this function. Functions can be used to create function scopes. At this point the function is like a translucent glass, inside the function you can see the variables outside, and in the function outside the function cannot see the variables.

function Foo() {

var i = 0; return function() { console. Log(i+ +);     }} var f1 = Foo(), f2 = Foo(); F1(); F1(); F2(); The answer is: 0 1 0

function Foo() {

var i = 0; return function() { console. Log(i+ +);     }}varF2 = Foo(); Foo () (); Foo () ();F2(); The answer is: 0 0 0

Variable scope and closure operations for JavaScript