conditional ternary

Summary

Returns one of two expressions depending on a condition. Also referred to as "if…else shorthand".

Syntax

test ? expression1 : expression2

test: Any Boolean expression.
expression1: An expression returned if test is true. May be a comma expression.
expression2: An expression returned if test is false. More than one expression may be a linked by a comma expression.

Examples

The ?: operator can be used as a shortcut for an if…else statement. It is typically used as part of a larger expression where an if…else statement would be awkward. This example creates a string containing “Good evening.” if it is after 6pm, or “Good day.” otherwise.

var now = new Date();
var greeting = "Good" + ((now.getHours() > 17) ? " evening." : " day.");

The equivalent code using a regular if…else statement would look as follows:

var now = new Date();
var greeting = "Good";
if (now.getHours() > 17)
    greeting += " evening.";
else
    greeting += " day.";

Attributions

Microsoft Developer Network: Article