condition ? expr1 : expr2
- An expression that evaluates to
- Expressions with values of any type.
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"
|ECMAScript 5.1 (ECMA-262)
The definition of 'The conditional operator' in that specification.
|ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Conditional Operator' in that specification.
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