Check If Two or More Variables Are All Equal to Zero in JavaScript

Question

What is the shortest way to check if two or more variables are equal to 0 in JavaScript?

I'm curious to know if there's something shorter than if(!x&&!y&&!z){...}.

Answer 1

(EDIT: This first part refers to the original phrasing of the question.)

First, (!x&&!y&&!z) returns a boolean, which makes ?true:false entirely redundant. It's basically like using

if (x == true)
  return true;
else if (x == false)
  return false;

instead of return x;.

That gives you

!x&&!y&&!z

(EDIT: The remainder still applies to the new version of the question.)

Now you could apply De Morgan's law. The above is equivalent to

!(x||y||z)

Which is the same length for 3 variables and longer for 2 variables. But for each variable beyond the third, you save one more character!

Lastly, if you know that your variables are numbers, you can also use the bitwise operator, i.e.

!(x|y|z)

If you actually need booleans (which I assume from your snippet), this doesn't work for the & case, because !x&!y&!z will give you an integer. Then again, in JavaScript it's often enough to have truthy or falsy values, in which case, that's a perfectly valid option.

Bonus tip: if you ever want to turn a truthy/falsy value (like a non-zero/zero number) into a boolean, don't use x?true:false either, but use !!x instead. !x is a boolean with the opposite truthiness/falsiness than x, so !!x is true for x truthy and false for x falsy.

Answer 2

Just an addendum.

In the special case where the block contains just a procedure call, you can replace

if(!x&&!y&&!z){call();}

by

x||y||z||call();

Answer 3

This function is obviously not the shortest until you have a lot of numbers to check (the poster did say "or more"). It verifies that all arguments are equal to zero.

function AllZero() {
    var args = Array.prototype.slice.call(arguments);
    args.push(0);
    return Math.min.apply(Math,args) === Math.max.apply(Math,args);
}

If you push a different number in the args.push(x) line, it will check that all of the arguments are equal to that number.