Operators - JavaScript by Example - page 114

Figure 5.20 The user is prompted to enter a number.

Figure 5.21 The user is prompted to enter another number.

Figure 5.22 The result is displayed.

5.3.1 The parseInt() Function

This function converts a string to a number. It starts parsing at the beginning of the
string and returns all integers until it reaches a noninteger and then stops parsing. If the
string doesn't begin with an integer, NaN (not a number) is returned. For example, par-
seInt(“150cats”) becomes 150 , whereas parseInt(“cats”) becomes NaN . However, if the
string begins with a leading 0x or 0X or a leading 0, then JavaScript assumes you want
the 0x to represent the beginning of a hex value and a single 0 to represent the start of
an octal value. You can also use octal and hexadecimal numbers. In the two-argument
format, the first argument to parseInt() is a string containing a number base (radix)
ranging from 2 to 36. The default is base 10. In the statement, parseInt(“17”, 8) , the
result is 15 . The first argument is the string to be parsed and the second argument, 8, is
the number base of the number (here, octal 17). The value returned is decimal 15 . Refer
to Tables 5.16 and 5.17.

FORMAT

parseInt(String, NumberBase); Default base is 10

parseInt(String);