How to Use Array.indexOf() for Comparing Multiple Items in JavaScript

You can also use Array.includes():

function checkMonth (month) {
const compareMonths = ['January', 'March', 'May', 'July', 'August', 'October',
 'December'];
// we can use ternary instead of if ...else
return compareMonths.includes(month) ? `${month} has 31 days` :
`${month} doesn't have 31 days`;
}
console.log(checkMonth ('July')); // "July has 31 days" console. log (checkMonth ('February')) // "February doesn't have 31 days"