Ternaries

(condition) ? (if) : (else)

console.log(pages > 1000 ? "over 1000" : "less than 1000");

Short Circuiting

in some conditions the operator will immediately return the first value and not even look at the 2nd value
falsy values: 0, '', null, undefined

&& operator

if 1st value is falsy, immediately returns the 1st value

const hasBook = true;
const hasMovie = false;
 
console.log(true && "Some string"); //"Some string"
console.log(false && "Some string"); // false
console.log(hasBook && "This has a book") //"This has a book"
console.log(hasMovie && "This has a movie") //false
 
console.log("hello" && "some string") //"some string"
console.log(0 && "some string")// 0

|| and ?? operator

if 1st value is truthy, immediately returns the 1st value

console.log(true || "hello"); //true
console.log(false || "hello"); //"hello"
 
// can be used to set default values!!
const spanishTranslation = book.translations.spanish || "NOT TRANSLATED";

be careful if the data is 0, this might not work as expected

??

you can use the nullish coalescing operator to solve this

const count = book.reviews.reviewsCount ?? "no data";

returns the 2nd value when the 1st is null or undefined!! (so not when it’s 0 or empty string)

Optional Chaining

 
function getTotalReviewCount(book) {
  const goodreads = book.reviews.goodreads.reviewsCount; //49701
  const librarything = book.reviews.librarything?.reviewsCount ?? 0; //0
  return goodreads + librarything;
}
 
console.log(getTotalReviewCount(book));

book.reviews.librarything?.reviewsCount ?? 0
- ? stops if the property before it is null or undefined and returns undefined (doesn’t throw errors)
- because it’sundefined ?? 0, the entire expression returns 0