Operators

• Vocabulary of operand

Unary operators

A unary operator is applied to a single operand, such as the increment operator ++ which can be used as x++ or ++x.

Math operators

• addition coerces to number

• adding bigints

Logic operators

• and, or, not

Bitwise operators

• and, or, xor, not

Nullish coalescence

The nullish coalescing operator ?? returns the right operand if the left operand is null.

A nullish coalescing operator can be used to "fall back" on a default value if the provided value is null or undefined. The || operator is also used to fall back on a default value if the left operand is falsy (i.e. 0, '', and false are all falsy and will cause the right operand to be produced).

Consider the example below, where a map stores the distance that each person is from a particular location. If we were to use the || operator instead of the nullish coalescence operator, the function would produce an unexpected Infinity for the name "Carol" where the distance is 0 (a falsy value).

Optional chaining

The optional chaining operator ? accesses an object property, and returns undefined if the value is undefined or null. This operator is often useful in accessing nested object properties that may be optional, or calling an object function that may not be defined.