number

a string that consists of optional whitespace followed by an optional minus sign followed by a Number followed by whitespace is converted to the IEEE 754 number that is nearest (according to the IEEE 754 round-to-nearest rule) to the mathematical value represented by the string; any other string is converted to NaN

boolean true is converted to 1; boolean false is converted to 0

a node-set is first converted to a string as if by a call to the string function and then converted in the same way as a string argument

an object of a type other than the four basic types is converted to a number in a way that is dependent on that type