Why is there no logical XOR?

Diving into XOR

Although Bitwise XOR (^) is a widespread player for numerical shadowboxing, JavaScript does not provide an explicit logical XOR. This lack can lead to some programmer head-scratching because other languages ply a logical XOR. In JavaScript, though, the logical operators && (AND) and || (OR) usually get the job done, with patterns like a != b standing in for boolean XOR, and more complex (a && !b) || (!a && b) expressions handling the heavier lifting.

Working with logical operators

JavaScript's logical operators, && and ||, have this curious trait of short-circuiting. This means if the first operand is enough to know the result of the expression, they'll simply ignore the second operand. Kinda like when you stop listening after "free pizza". A XOR operation would reluctantly evaluate both operands, complicating things.

Casting numeric to boolean

Numeric results from bitwise XOR might seem like proverbial apples in the oranges of logical contexts. Fear not! Just need a quick genre switch:

var logicalXOR = !!((a && !b) || (!a && b));
// or the explicit way:
var logicalXOR = Boolean(a) !== Boolean(b);


Falsy, truthy, and logical XOR

JavaScript's internal logic concerning truthy and falsy values can complicate a logical XOR implementation. This remains consistent with universe logic where everything is complicated. Experiments have shown that explicitly coercing values to boolean increases success rate significantly.

Exploring XOR alternatives

Variety is the spice of XOR:

var xorAlt1 = !!( Number(!!a) ^ Number(!!b) );
// Coerces 'a' and 'b' to numbers after a Boolean reality check, then XOR'em

var xorAlt2 = a != b;
// When 'a' and 'b' are booleans already, no fancy movements needed.


Chill out and find what variation suits best your use case, keeping in mind that each has its pros and cons.

XOR in action

In the practical world, XOR logic gets to play in:

• Toggle functions: Like a light switch, you can turn a feature on and off.
• Feature access: Imagine granting a permission if a user has either one but not both of two keys.

XOR: Caution ahead

When dealing with XOR, don't trip over these common stones:

• Coercion conundrums: Ensure you understand JavaScript's type coercion.
• Unwanted side-effects: Avoid XOR with expressions that could trigger side effects.
• Readability issues: XOR can have a steep learning curve for your teammates, so choose wisely!