Converts a string to an integer.
The parseInt function returns an integer value equal to the number contained in numString. If no prefix of numString can be successfully parsed into an integer, NaN (not a number) is returned.
You can test for NaN using the isNaN function.
Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported in Store apps (Windows 8 and Windows Phone 8.1). See Version Information.