JavaScript Logical Operators
Logical Operators
Logical operators are used to combine boolean expressions.
Logical operators can be used to modify the results of comparisons.
Typically, you will use a comparison operator to check a condition, and a logical operator to combine conditions into more complex logic.
JavaScript Logical Operators
Logical operators are used to determine the logic between variables or values.
Given that x = 6 and y = 3, the table below explains the logical operators:
| Oper | Name | Example | Try it |
|---|---|---|---|
| && | AND | (x < 10 && y > 1) is true | Try it » |
| || | OR | (x === 5 || y === 5) is false | Try it » |
| ! | NOT | !(x === y) is true | Try it » |
JavaScript Logical AND
The && operator returns true
if both expressions are true,
otherwise false:
JavaScript Logical OR
The || operator returns true if one or both expressions
are true, otherwise false:
JavaScript Logical NOT
The NOT operator (!) returns true for false expressions
and false for true expressions.
The Nullish Coalescing Operator (??)
The ?? operator returns the right operand when the left operand is
nullish (null or undefined),
otherwise it returns the left operand.
When programming, a lot of values can be falsey (like 0, empty strings, false, undefined, null, NaN).
However, sometimes you want to check if a variable is nullish
(either undefined or null),
like when it is okay for a variable to be an empty string, or a false value.
Then you can use the nullish coalescing operator.
Browser Support
?? is an ES2020 feature.
ES2020 is fully supported in all modern browsers since September 2020:
| Chrome 85 |
Edge 85 |
Firefox 79 |
Safari 14 |
Opera 71 |
| Aug 2020 | Aug 2020 | Mar 2020 | Sep 2020 | Sep 2020 |
