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In JavaScript...
'\t\n ' == false // true
I can assume that any string that consists solely of whitespace characters is considered equal to false in JavaScript.
According to this article, I figured that false would be converted to 0, but was unable to find mention of whitespace considered equal to false using Google.
Why is this? Is there some good reading on the subject besides digging into the ECMAScript spec?
437
Because == (and === ) test to see if two objects are the same object and not if they are identical objects.
The answer is because "false" is a string (as Gerardo Furado pointed out in the comments), the test you are making is equivalent to false = "hello". Javascript does not look at the word in the string to determine if it is a boolean and then try to get the value from that.
The '==' operator tests for abstract equality i.e. it does the necessary type conversions before doing the equality comparison. But the '===' operator tests for strict equality i.e it will not do the type conversion hence if the two values are not of the same type, when compared, it will return false.
Types of x and y are checked when x == y is to be checked. If no rule matches, a false is returned. For [] == true , rule 7 matches, so a result of [] == ToNumber(true) is returned i.e. false is returned. Reason you're getting the same result for ![]
This page provides a good summary of the rules.
Going by those rules, the '\t\n ' is converted in a number (Number('\t\n') ==> 0), and the false is converted into a number (Number(false) ==> 0), and hence the two are equal.
Alex's answer is also a good breakdown of the particular case of '\t\n ' == false.
An important distinction is that '\t\n ' is not falsy. For example:
if ('\t\n ') alert('not falsy'); // will produce the alert
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