How do you read this JavaScript code? (var1 ? var2:var3)

Question

I've seen this format used in JavaScript code, but can't find a good source for the meaning.

Edit for a follow-up:

Thanks for all the quick answers! I figured it was something like that. Now, for bonus points:

can you use (var1 ? var2)

to do the same thing as

    if (var1) {
        var2
    }

?

Answer 1

It's known as a ternary (because it has three operands) conditional (because it's an if/else/then) operator.

It is evaluated to a value, so you would usually use it to assign a value, such as:

var result = condition ? value1 : value2;

Which is equivalent to:

var result;
if (condition == true) {
  result = value1;
} else {
  result = value2;
}

An example:

var message = "Length is " + len + " " + (len==1 ? "foot" : "feet");

Note ?: is the full operator. It's not a ? and : operator, so ? by itself is meaningless in Javascript.

Answer 2

Its a conditional operator.

It is

if var1 then var2 else var3

Read more here

Conditional Operator

The conditional operator is the only JavaScript operator that takes three operands. This operator is frequently used as a shortcut for the if statement.