In newer JavaScript standards like ES5 and ES6 you can just say
> Boolean(0) //false
> Boolean(null) //false
> Boolean(undefined) //false
all return false, which is similar to Python's check of empty variables. So if you want to write conditional logic around a variable, just say
if (Boolean(myvar)){
// Do something
}
here "null" or "empty string" or "undefined" will be handled efficiently.