In JavaScript, the indexOf() method returns the first index at which a specified element can be found in an array. If it does not exist in the array, -1 is returned instead. Similarly, lastIndexOf() returns the last index where an element appears or -1 if it doesn't exist within the array. These methods are incredibly useful when searching for elements and are commonly used in various coding instances.
The lastIndexOf() method returns the last index at which
a given element can be found in the array, or -1 if it is not present. The array is
searched backwards, starting at fromIndex.
Source: Mozilla, https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/lastIndexOf
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