Index Of / Last Index Of

indexOf(value)

• Returns the first index of the object being sought, or -1 if it does not exist in the array. Searches from beginning to end of the array.

let obj = {name : 'test'};
let arr = [1,2,3,'kiwi', obj];

arr.indexOf(3); // 2
arr.indexOf('kiwi'); // 3
arr.indexOf(obj); // 4

arr.indexOf('not found'); // -1

lastIndexOf(value)

• Returns the last index of the object being sought, or -1 if it does not exist in the array. Searches from the end to the beginning of the array.

let arr = [1,2,3,4,3,2,1];

arr.lastIndexOf(1); // 6
arr.lastIndexOf(2); // 5
arr.lastIndexOf(3); // 4
arr.lastIndexOf('not found'); // -1

Skill Drill

1. Create the following array:

   let arr = ["Apple", "Banana", "Coconut", "Apple"];
   

2. Write a function contains that uses indexOf to determine if the value is in the array or not.

3. Use the lastIndexOf function on arr to determine at what index the string "Apple" is stored.

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