What is a “closure” in JavaScript??

Answer: A closure is an inner function that has access to the variables in the outer (enclosing) function’s scope chain.
The closure has access to variables in three scopes, specifically:
(1) variable in its own scope. (2) variables in the enclosing function’s scope. (3) global variables.
function OuterFunction() { var outerVariable = 100; function InnerFunction() { alert(outerVariable); } return InnerFunction; } var innerFunc = OuterFunction(); innerFunc(); // 100