0 in javascript is a falsy value.
var v = 0;
if(v) {
  console.log("true");
} else {
  console.log("false");
}number % 2 will return either 0 (which is falsy) or 1 (which is truthy). So if the number is even then number % 2 will return 0 and the condition of the ternary will be false, …
solved Javascript ternary operator hidden logic