Conditional (ternary) operator
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
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 an alternative to an if...else
statement.
Try it
Syntax
condition ? exprIfTrue : exprIfFalse
Parameters
condition
-
An expression whose value is used as a condition.
exprIfTrue
-
An expression which is executed if the
condition
evaluates to a truthy value (one which equals or can be converted totrue
). exprIfFalse
-
An expression which is executed if the
condition
is falsy (that is, has a value which can be converted tofalse
).
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 basic example
const age = 26;
const beverage = age >= 21 ? "Beer" : "Juice";
console.log(beverage); // "Beer"
Handling null values
One common usage is to handle a value that may be null
:
const greeting = (person) => {
const 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;
}
This is equivalent to the following if...else
chain.
function example() {
if (condition1) {
return value1;
} else if (condition2) {
return value2;
} else if (condition3) {
return value3;
} else {
return value4;
}
}
Specifications
Specification |
---|
ECMAScript Language Specification # sec-conditional-operator |
Browser compatibility
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