Conditional (ternary) operator

The conditional (ternary) operator is the only JavaScript operator that takes three operands: a condition followed by a question mark (?), then an expression to execute if the condition is truthy followed by a colon (:), and finally the expression to execute if the condition is falsy. This operator is frequently used as a shortcut for the if statement.

Syntax

condition ? exprIfTrue : exprIfFalse

Parameters

condition
An expression whose value is used as a condition.
exprIfTrue
An expression which is evaluated if the condition evaluates to a truthy value (one which equals or can be converted to true).
exprIfFalse
An expression which is executed if the condition is falsy (that is, has a value which can be converted to false).

Description

Besides false, possible falsy expressions are: null, NaN, 0, the empty string (""), and undefined. If condition is any of these, the result of the conditional expression will be the result of executing the expression exprIfFalse.

Examples

A simple example

var age = 26;
var beverage = (age >= 21) ? "Beer" : "Juice";
console.log(beverage); // "Beer"

Handling null values

One common usage is to handle a value that may be null:

let greeting = person => {
    let name = person ? person.name : `stranger`
    return `Howdy, ${name}`
}

console.log(greeting({name: `Alice`}));  // "Howdy, Alice"
console.log(greeting(null));             // "Howdy, stranger"

Conditional chains

The ternary operator is right-associative, which means it can be "chained" in the following way, similar to an if … else if … else if … else chain:

function example() {
    return condition1 ? value1
         : condition2 ? value2
         : condition3 ? value3
         : value4;
}

// Equivalent to:

function example() {
    if (condition1) { return value1; }
    else if (condition2) { return value2; }
    else if (condition3) { return value3; }
    else { return value4; }
}

Specifications

Browser compatibility

BCD tables only load in the browser

See also