Inserting Elements

The insert method is intended to add an element to the list at a specified index. The first argument should be an integer (the index), and the second argument should be the value you want to insert.

# Python

alist = ['apple', 'banana', 'cherry']
alist.insert(index, value)
alist.insert('1', 'kiwi')  # alist is now ['apple', 'kiwi', 'banana', 'cherry']

The indexOf method searches the array for the specified element, in this case, ‘apple’. The splice method is used to insert elements into the array.

%%js
// Javascript

let alist = ['apple', 'banana', 'cherry'];

// Find the index of 'apple'
const index = alist.indexOf('apple');  // index will be 0 because 'apple' is at the first position of the array.

// Insert 'a' before 'apple'
if (index !== -1) {
   alist.splice(index, 0, 'kiwi'); // 0 indicates no elements to remove
}

console.log(alist); // Output: ['kiwi', 'apple', 'banana', 'cherry']

Removing Elements

The remove method is used to remove the first occurrence of a specified value from a list. In this case, you’re trying to remove 'kiwi'.

# Python

aList.remove('kiwi')  # Removes 'kiwi' from the list
print(aList)  # Output: ['apple', 'banana', 'cherry',]

Once again use the indexOf method to find the index of 'kiwi'. If ‘kiwi’ is found, the splice method is used. This method modifies the list. The first argument (index) is the starting index (where to begin removing items), and the second argument (1) is the number of items to remove. Here, it removes one item starting from index 3, effectively removing ‘kiwi’.

%%js
// Javascript

let aList = ['apple', 'banana', 'cherry', 'kiwi', 'grape']; // initial list
let index = aList.indexOf('kiwi'); // Find the index of 'kiwi'

if (index !== -1) {
   aList.splice(index, 1);  // Removes 'kiwi' from the list
}
console.log(aList);  // Output: ['apple', 'banana', 'cherry', 'grape']

Deleting an element

This line uses the del statement to remove the item at index 2 from the list.

# Python
aList = ['apple', 'banana', 'cherry', 'grape'] # initial list
del aList[2]  # Deletes 'cherry' at index 2
print(aList)  # Output: ['apple', 'banana', 'grape']

This line uses the splice method to remove an element from the array. The splice method takes two arguments: The first argument (2) specifies the starting index from which to begin removing elements. Here, it points to the element at index 2, which is 'cherry'. The second argument (1) indicates how many elements to remove starting from that index. In this case, it will remove 1 element.

%%js
// Javascript

let aList = ['apple', 'banana', 'cherry', 'grape'];

// Delete the element at index 2
aList.splice(2, 1); // Removes 1 element at index 2

console.log(aList); // Output: ['apple', 'banana', 'grape']

Popcorn Hack

  • Try adding an element to your list
  • Try deleting a different element from your list