Interpolation in template literals

Backticks turn strings into “template literals” in JavaScript. They allow you to interpolate variables, the results of calculations, and even the return values of function calls.

const age = 4

// the “old” way to get the value of `age` into a strings
const concatenation = 'Little Bobby is ' + age + ' years old.'

// use `${expression}` to do the same in a template literal
const interpolation = `Little Bobby is ${age} years old.`

// an expression can be a calculation
const withCalculation = `Next year, Bobby will be ${age + 1} years old.`

// you can even use the return value of a function call in an expression
const withFunctionCall = `${age} years are ${yearsInDays(age)} days.`