How do you use the ? : (conditional) operator in JavaScript?

Question

In simple words, what is the ?: (conditional, "ternary") operator and how can I use it?

Answer 1

It's called the 'ternary' or 'conditional' operator.

Example

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. For example:

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

The example creates a string containing "Good evening." if it is after 6pm. The equivalent code using an if...else statement would look as follows:

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

From MSDN JS documentation.

Basically it's a shorthand conditional statement.

Also see:

• Operator precedence with Javascript Ternary operator
• Wikipedia