While you create the JavaScript function within another function and the inner function freely access all the variable of OUTER function. i.e.

function ourterFun(i) {
var VAR1 = 3;
function innerFun(j) {
console.log(i + j + (++var1)); // It will return the 16.
}
innerFun(10);
}
ourterFun(2); // Pass an ARGUMENT 2

The output will get 16 because innerFun() function can access to the argument "i" & variable "var1" but both are define in the outerFun() function that is closure.

That means simply accessing variable OUTSIDE of your scope create a closure.

// OR Other WAYS
function ourterFun(i) {
var var1 = 3;
return function (j) {
console.log(i + j + (++var1)); // It will return the 16.
}
}
var innerFun = ourterFun(2); // innerFun() function is now a closure.
innerFun(10);

While you create the JavaScript function within another function and the inner function freely access all the variable of outer function. i.e.

function ourterFun(i) {
var var1 = 3;
function innerFun(j) {
console.log(i + j + (++var1)); // It will return the 16.
}
innerFun(10);
}
ourterFun(2); // Pass an argument 2

The output will get 16 because innerFun() function can access to the argument "i" & variable "var1" but both are define in the outerFun() function that is closure.

That means simply accessing variable outside of your scope create a closure.

// OR Other WAYS
function ourterFun(i) {
var var1 = 3;
return function (j) {
console.log(i + j + (++var1)); // It will return the 16.
}
}
var innerFun = ourterFun(2); // innerFun() function is now a closure.
innerFun(10);