parseInt Function (JavaScript)

Converts a string to an integer.


parseInt(numString, [radix])   


Required. A string to convert into a number.

Optional. A value between 2 and 36 that specifies the base of the number in numString. If this argument is not supplied, strings with a prefix of '0x' are considered hexadecimal. All other strings are considered decimal.


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.

parseInt("abc");     // Returns NaN.  
parseInt("12abc");   // Returns 12.  

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.

Applies To: Global Object


Starting in Internet Explorer 9 standards mode, the parseInt function does not treat a string that has a prefix of '0' as an octal. When you are not using the parseInt function, however, strings with a prefix of '0' can still be interpreted as octals. See Data Types for information about octal integers.

See Also

isNaN Function
parseFloat Function
String Object
valueOf Method (Object)