Preview:
const numbers = [1, 2, 3, 4, 5, 3, 1, 2]

console.log(numbers.lastIndexOf(2)) // 7
console.log(numbers.lastIndexOf(0)) // -1
console.log(numbers.lastIndexOf(1)) //  6
console.log(numbers.lastIndexOf(4)) //  3
console.log(numbers.lastIndexOf(6)) // -1
downloadDownload PNG downloadDownload JPEG downloadDownload SVG

Tip: You can change the style, width & colours of the snippet with the inspect tool before clicking Download!

Click to optimize width for Twitter