Javascript closures and side effects in plain English? (separately)

Question

I\'ve been reading some JavaScript books and I always hear about closures and side effects. For some reason I can\'t understand what they really are. Can anyone explain to m

Answer 1

Exemple

function outer() {
    var outerVar;

    var func = function() {
        var innerVar
        ...
        x = innerVar + outerVar
    }
    return func
}

When outer() die, function func() continue livе and this use practical