Q:

JavaScript - Shorthand of "Or" inside an if statement

Is there a shorthand for "Or" condition inside an if statement, I feel it's stupid to be repetitive, in the below case "a" variable is repetitive to check all the "Or" conditions:
  if(a ! = 'Cancelled' || a ! = 'Rejected' || a ! = 'Delivered' || a ! = 'Confirmed'){

    //execute something here

 }

A:

if (['Cancelled', 'Rejected', 'Delivered', 'Confirmed'].indexOf(a) == -1) {
  // do stuff here
}

