Related questions
JavaScript check if variable exists (is defined/initialized)
Which method of checking if a variable has been initialized is better/correct?
(Assuming the variable could hold anything (string, int, object, function, etc.))
if (elem) { // or !elem
or
if (typeof(elem) !== 'undefined') {
or
if (elem != null) {
How do JavaScript closures work?
How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?
I have seen the Scheme example given on Wikipedia, but …