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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 »

The Nullish Coalescing Operator (??)

The ?? operator returns the first argument if it is not nullish (null or undefined).

Otherwise it returns the second argument.

Example

let name = null;
let text = "missing";
let result = name ?? text;
Try it Yourself »

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

Given that x = 6 and y = 3, the table below explains the logical operators:

Operator Description 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 »

The Conditional (Ternary) Operator

The conditional operator is a shorthand for writing conditional if...else statements.

It is called a ternary operator because it takes three operands.

Syntax

(condition) ? value1:value2

Example

let voteable = (age < 18) ? "Too young":"Old enough";
Try it Yourself »

If the variable age is a value below 18, the value of the variable voteable will be "Too young", otherwise the value of voteable will be "Old enough".

The Nullish Coalescing Operator (??)

The ?? operator returns the first argument if it is not nullish (null or undefined).

Otherwise it returns the second argument.

Example

let name = null;
let text = "missing";
let result = name ?? text;
Try it Yourself »

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

The Optional Chaining Operator (?.)

The ?. operator returns undefined if an object is undefined or null (instead of throwing an error).

Example

// Create an object:
const car = {type:"Fiat", model:"500", color:"white"};
// Ask for car name:
document.getElementById("demo").innerHTML = car?.name;
Try it Yourself »

The optional chaining operator is supported in all browsers since March 2020:

Chrome 80 Edge 80 Firefox 72 Safari 13.1 Opera 67
Feb 2020 Feb 2020 Jan 2020 Mar 2020 Mar 2020

Example

let x = 6;
let y = -3;
let z = (x > 0 || y > 0)
Try it Yourself »

The Optional Chaining Operator (?.)

The ?. operator returns undefined if an object is undefined or null (instead of throwing an error).

Example

// Create an object:
const car = {type:"Fiat", model:"500", color:"white"};
// Ask for car name:
document.getElementById("demo").innerHTML = car?.name;
Try it Yourself »

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
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