Conditional (ternary) Operator
The conditional (ternary) operator is the only JavaScript operator that takes three operands. This operator is frequently used as a shortcut for the if
statement.
Syntax
condition ? expr1 : expr2
Parameters
condition
- An expression that evaluates to
true
orfalse
.
expr1
,expr2
- Expressions with values of any type.
Description
If condition
is true
, the operator returns the value of expr1
; otherwise, it returns the value of expr2
. For example, to display a different message based on the value of the isMember
variable, you could use this statement:
"The fee is " + (isMember ? "$2.00" : "$10.00")
You can also assign variables depending on a ternary result:
var elvisLives = Math.PI > 4 ? "Yep" : "Nope";
Multiple ternary evaluations are also possible (note: the conditional operator is right associative):
var firstCheck = false, secondCheck = false, access = firstCheck ? "Access denied" : secondCheck ? "Access denied" : "Access granted"; console.log( access ); // logs "Access granted"
You can also use ternary evaluations in free space in order to do different operations:
var stop = false, age = 16; age > 18 ? location.assign("continue.html") : stop = true;
You can also do more than one single operation per case, separating them with a comma:
var stop = false, age = 23; age > 18 ? ( alert("OK, you can go."), location.assign("continue.html") ) : ( stop = true, alert("Sorry, you are much too young!") );
You can also do more than one operation during the assignation of a value. In this case, the last comma-separated value of the parenthesis will be the value to be assigned.
var age = 16; var url = age > 18 ? ( alert("OK, you can go."), // alert returns "undefined", but it will be ignored because // isn't the last comma-separated value of the parenthesis "continue.html" // the value to be assigned if age > 18 ) : ( alert("You are much too young!"), alert("Sorry :-("), // etc. etc. "stop.html" // the value to be assigned if !(age > 18) ); location.assign(url); // "stop.html"
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2017 Draft (ECMA-262) The definition of 'Conditional Operator' in that specification. |
Draft | |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Conditional Operator' in that specification. |
Standard | |
ECMAScript 5.1 (ECMA-262) The definition of 'The conditional operator' in that specification. |
Standard | |
ECMAScript 1st Edition (ECMA-262) The definition of 'The conditional operator' in that specification. |
Standard | Initial definition. Implemented in JavaScript 1.0. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/operators/conditional_operator