Why is there no logical xor in JavaScript?

Question

Why is there no logical xor in JavaScript?

Answer 1

Check out:

• Logical XOR in JavaScript

You can mimic it something like this:

if( ( foo && !bar ) || ( !foo && bar ) ) {
  ...
}

Answer 2

JavaScript traces its ancestry back to C, and C does not have a logical XOR operator. Mainly because it's not useful. Bitwise XOR is extremely useful, but in all my years of programming I have never needed a logical XOR.

If you have two boolean variables you can mimic XOR with:

if (a != b)

With two arbitrary variables you could use ! to coerce them to boolean values and then use the same trick:

if (!a != !b)

That's pretty obscure though and would certainly deserve a comment. Indeed, you could even use the bitwise XOR operator at this point, though this would be far too clever for my taste:

if (!a ^ !b)

Answer 3

The reason there is no logical XOR (^^) is because unlike && and || it does not give any lazy-logic advantage. That is the state of both expressions on the right and left have to be evaluated.

Answer 4

Yes, Just do the following. Assuming that you are dealing with booleans A and B, then A XOR B value can be calculated in JavaScript using the following

var xor1 = !(a === b);

The previous line is also equivalent to the following

var xor2 = (!a !== !b);

Personally, I prefer xor1 since I have to type less characters. I believe that xor1 is also faster too. It's just performing two calculations. xor2 is performing three calculations.

Visual Explanation ... Read the table bellow (where 0 stands for false and 1 stands for true) and compare the 3rd and 5th columns.

!(A === B):

| A | B | A XOR B | A === B | !(A === B) |
------------------------------------------
| 0 | 0 |    0    |    1    |      0     |
| 0 | 1 |    1    |    0    |      1     |
| 1 | 0 |    1    |    0    |      1     |
| 1 | 1 |    0    |    1    |      0     |
------------------------------------------

Enjoy.

Answer 5

The XOR of two booleans is simply whether they are different, therefore:

Boolean(a) !== Boolean(b)

Answer 6

In Typescript (The + changes to numeric value):

value : number = (+false ^ +true)

So:

value : boolean = (+false ^ +true) == 1