JavaScript True, False: Checking for Boolean Values
Checking if a value is true or false is simple in JavaScript. All values evaluate to true, except for:
0
-0
null
undefined
NaN
empty string
false
For example, the following results in false being output since the empty string evaluates to false.
var testVar = ''
if (testVar)
document.write('true');
else
document.write('false');
It should also be noted that the literal strings '0' and 'false' evaluate to true.
