The Array lastIndexOf() method returns the last position of a specified value, searching from right to left, and returning -1 if the value is not found.

<!-- html element to place output -->
<p id='my_cars'></p>

// array
let cars = ['Maserati', 'Ferrari', 'Maserati', 'Alfa Romeo'];

// find the key of the last occurence of Maserati
let my_index = cars.lastIndexOf('Maserati');

// cycle through the keys and output the last occurence to the HTML element
document.getElementById('my_cars').innerHTML = my_index;

The way this works (see Syntax section below):

• The lastIndexOf() method cycles through the array starting from the end looking for the index of a specified value

2

array.lastIndexOf(item, start)

Parameter	Description
item	The value to search for (required)
start	Where to start the search; negative start values counts from the last element searching from right to left (default array.length-1)

---