Closure meaning: And here comes the

And here comes the closure part: The closure of a lambda expression is this particular set of symbols defined in the outer context (environment) that give values to the free symbols in this expression, making them non-free anymore. A database closure might refer to the closure of all of the database attributes. According to the definitions above, this closure would be the set of all attributes of the database itself. The closure (computer science) term that you linked to is not related to closure in databases but the mathematical closure is. Closure is the end or the closing down of something . It can be physical — like the closure of your local library — or emotional, like the closure you experience when you finally come to terms with the end of a romance. That's the magic, and frustration, of closure . "JavaScript Functions close over the scope they are declared in, and retain access to that scope even as variable values inside of that scope change." Using let instead of var solves this by creating a new scope each time the for loop runs, creating a separated scope for each function to close over.