Lesson Sunday

Template literals are a spoonful of syntactic sugar and another popular feature in ES6. They're especially useful when concatenating strings or inserting variables into strings.

A lot of other languages have this same feature, too. For example, template literals are called string interpolation in both Ruby and C#. It's also a lot easier to use than concatenation, especially with longer strings.

Template Literals

Here's an example of how we'd insert a variable into a string prior to ES6. (In the following example, ignore the fact that we wouldn't use let prior to ES6.)

let language = "JavaScript";
let adjective = "fun";

let concatenatedString = language + " is " + adjective + " to learn!";

String concatenation is useful but it quickly becomes painful. We can make this process relatively painless using template literals. Here's an example using the same variables from above:

let stringLiteral = `${language} is ${adjective} to learn!`;

There are two syntax rules to remember with template literals:

  1. First, we need to surround the string with the backtick symbol instead of quotes.
  2. Second, any variable or expression needs to be put inside of ${ }.

Using Template Literals for Expressions

Note that template literals ${ } can contain any expression, not just a variable. For instance, we could do this:

let length = 2;
let width = 3;
let rectangleArea = `The area of a rectangle with length ${length} and width ${width} is ${length * width}.`;

In the example above, we're calculating length * width inside the template literal. We can compute any JS code inside a template literal as long as it's inside of ${}. Keep in mind that while you can do this, you probably shouldn't, since it could quickly make your code less readable.

Creating Multi-Line Strings

One last thing. Backticks can be used to create multi-line strings. It's unlikely you'll need this functionality much, but it's still good to know. Here's an example to try out in the DevTools console:

> const multiLineString = `This is not a good
haiku about JavaScript code:
template literals.`;
> console.log(multiLineString);
This is not a good
haiku about JavaScript code:
template literals.

If we don't print multiLineString in a console.log(), we'll see our line breaks are preserved by the new line character \n:

'This is not a good\nhaiku about JavaScript code:\ntemplate literals.'

To see more examples, visit the MDN documentation on template literals.

Lesson 3 of 14
Last updated July 7, 2022