directly lower than || and directly higher than the conditional (ternary) operator.

Operator precedence for the nullish coalescing operator is fifth-lowest.

Javascript double question mark is a logical operator that takes two values and returns the right-hand value if the left-hand value is undefined or null, else returns its left-hand value.Nullish coalescing operator is a new feature introduced in this ECMA proposal and is denoted by the double question marks ?.

However, Y() returned false hence the right-hand side expression was not evaluated.ĭirectly combining the logical AND or OR operator with the nullish coalescing operator will result in a Synta圎rror, as in the following example:.

As we can see on X() ? Z(), X() returned undefined, so both expressions were evaluated.

Define three functions X() which returns undefined, y() which returns false and Z() that returns a string.

logs 'Y was called' then 'false' // as Y() returned false (and not null or undefined), the right // hand side expression was not evaluated logs 'X was called' then 'Z was called' and then 'foo' // as X() returned undefined so both expressions are evaluated console.

Javascript questionmark operator