Functions

1. isOnline() when runned in browser environment, then returns online status, when runned in nodejs then returns null

2. isEmpty(value) returns true if either the argument is null or undefined

3. isNotEmpty(value) returns true if neither the argument is null nor undefined

4. isBrowser() return if the current environment is browser or not

5. isString(value), isFunction(value), isNumber(value), isUndefined(value), isNull(value), isObject(value), isBoolean(value)