Vi. JavaScript data type (ii)

1.4 Boolean Type

Literal value: True, False

You can call the Boolean () function on a value of any data type, and always return a Boolean value.

Data type	The value converted to true	Value converted to False
Boolean	True	False
String	Any non-empty string	"" (empty string)
Number	Any non-0 digits (including infinity)	0 and Nan
Object	Any object	Null
Undefined	N/A	Undefined

1.5 Number Type

var intnum = 55; Integer

var floatNum1 = 1.; No digits after the decimal point--resolves to 1

var floatNum2 = 10.0; integer--resolves to 10

var floatnum = 3.125e7; equals 31250000

var 0.2 0.1 ; alert (a//  0.30000000000000004

NaN, or non-numeric (not a number) is a special value that represents an operand that would have returned a numeric value.

No value is returned (this will not throw an error).

// false

Alert (IsNaN (NaN)); // true    Alert (IsNaN (10)); // False (10 is a numeric value)    // False (can be converted to a value of ten)    Alert (IsNaN ("Blue")); // true (cannot be converted to numeric value)    Alert (IsNaN (true//False (can be converted to a value of 1)

There are 3 functions that can convert non-numeric values to numeric values: Number (), parseint (), and parsefloat ().

Vi. JavaScript data type (ii)