wtfjs: negative mod, equality

wtfjs_-%=.js

// Check if a thing is rotated 90°.
function isRotatedOffAxis (rotation) {
  return rotation % 180 !== 0;
}
 
// Hm, what about -180?
console.log(-180 % 180);  // -0. wtf #a
 
// So then why is this ok?
isRotated(-180);  // false
 
// Because:
console.log(0 === -0);  // true. wtf #b