JavaScript Closure Example

This example shows how you can create a closure. The add function provides the closure and it returns the addToNum1 function. The add5 variable then calls the add function passing in the argument 5. Finally calling the add5 function and passing in the argument 2 will return 7.

var add = function(num) {
    var num1 = num; //stays at 5
    
    var addToNum1 = function(num2) {
        return num1 + num2;
    }
    return addToNum1;
};

var add5 = add(5);
add5(2); // 7
add5(3); // 8

For a more detailed article on closures take a look at the MDN website.