I have seen most of the developers using parseInt to convert a string to a number. Here we need to understand that What does this parseInt will do, what all parameters it accepts.
ParseInt will behave differently depending upon the parameters given.
for example ::
parseInt("10") ---> Result :: 10
parseInt("9") ---> Result :: 9
parseInt("109") ---> Result :: 109
Have you ever tried giving "08" or "09", it will give "0" as result. I have seen in most of the javascript calendar controls using parseInt where the number passed to it will be in two digit format. So when the date contains 09 0r 08, all calculations will go wrong.
The above scenario is just a simple example of making mistakes. Lot of people will do this kind of mistakes without understanding the actual purpose of available functions and properties.
So whenever you go for parseInt for integer conversion, please do practice the below snippet ::
parseInt("08",10) ---> Result :: 8
parseInt("09",10) ---> Result :: 9
parseInt("018",10) ---> Result :: 18
For more info