Logical operators

Learn boolean logic with &&, || and !.

Logical operators

Logical operators combine boolean values: && (and), || (or), ! (not).

&& returns true if both conditions are true: age >= 18 && hasLicense. || returns true if at least one is true: isWeekend || isHoliday.

! inverts the value: !isActive. These operators are essential tools for combining conditions.

Short-circuit

Logical operators short-circuit: when the result is determined, they do not evaluate the other side.

For example, in false && something, since the left side is false, the result is definitely false; something is not evaluated. The same goes for true || something.

This is used for safe access: user && user.name. If user is null, the right side does not run; no error is thrown.

Exercise Logical expression

Declare age = 20 and hasLicense = true. Compute canDrive as age >= 18 && hasLicense. Call console.log(canDrive).

Show example solution

const age = 20;
const hasLicense = true;
const canDrive = age >= 18 && hasLicense;
console.log(canDrive);

Test yourself

What does the && operator return?
- Adds two numbers
- Compares two values
- Returns true if both conditions are true
- Returns true if one condition is true
Show answer

Returns true if both conditions are true — && returns true if both conditions are true.
Match the operators

&&

Logical and
||

Logical or
!

Not
>=

Greater or equal

&& example

const isValid = age >= 18 ____ hasLicense;

Show answer

const isValid = age >= 18 && hasLicense;

Next lesson: Nullish coalescing

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