What is a Ternary Operator in JavaScript?

A ternary operator is a way to write if/else statements in one line, however if you've never heard of them before, they can be tricky to understand.

Anatomy of a Ternary Operator

They consist of 3 fundamental components.

1. A condition followed by a question mark (?)
2. An expression to execute if the condition is truthy
3. An expression to execute if the condition is falsy

A ternary operator is written like this: isTrue ? true : false. We have our condition isTrue. It's the variable we are checking. It represents if (isTrue) in a traditional if statement.

The true after the question mark represents tha expression we will execute if the variable we are checking returns a truthy value.

The false is the expression we will execute if the variable is falsy.

It took me a while to figure out how to actually write ternary operators because I didn't understand them, so I stuck with if statements until I forced myself to learn them.

Since then, I use them quite often, however ternary operators shouldn't always be used, in my opinion.

I use ternary operators when I need a quick check if something is true or false. Use whatever gets the job done, but also provides decent readability.

How it differs from an if statement

Ternary operators work more like if/else statements.

If I were to write...

isTrue ? true

It would be like writing...

if (isTrue) {}

The difference is our ternary operator (the first code block) will fail whereas our if statement will succeed.

It needs an expression to execute for a truthy or falsy result. With that said, ternary operators are more like if/else statements.

They really work liike...

if (isTrue) {
  truthy()
} else {
  falsy()
}

A complete example

In order to wrap this up with a pretty bow, I'll include a full example of how a ternary operator can be used.

const favouriteColour = "blue"

const isBlue = favouriteColour === "blue" ? "it's true! it's blue!" : "it's not blue :("

console.log(isBlue) // "it's true! It's blue!"

// Let's change our fav colour

const favouriteColour = "red"

const isBlue = favouriteColour === "blue" ? "it's true! it's blue!" : "it's not blue :("

console.log(isBlue) // "it's not blue :("

Ternary operators are amazing to use. If you're having a tough time understanding it, just keep practicing and working at it. As with anything that is unknown, through consistent practice, you'll understand it before you know it.

Just remember favouriteColour === "blue" ? is our condition, ? truthy : is our code to execute if it's truthy, and : falsy; is our code to execute if it's not.