Array Deletion at End in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to remove the last element from the array.

DSA Javascript

let arr = [1, 2, 3, 4];
arr.[1]();
console.log(arr);

Drag options to blanks, or click blank then click option'

Apop

Bpush

Cshift

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using push() instead of pop() adds an element instead of removing.

Using shift() removes the first element, not the last.

The pop() method removes the last element from an array.

2fill in blank

medium

Complete the code to remove the last element and store it in a variable.

DSA Javascript

let fruits = ['apple', 'banana', 'cherry'];
let last = fruits.[1]();
console.log(last);

Drag options to blanks, or click blank then click option'

Aunshift

Bpush

Cshift

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using push() which adds elements instead of removing.

Using shift() which removes the first element.

pop() removes and returns the last element of the array.

3fill in blank

hard

Fix the error in the code to correctly remove the last element.

DSA Javascript

let numbers = [10, 20, 30];
numbers.[1];
console.log(numbers);

Drag options to blanks, or click blank then click option'

Apush()

Bpop

Cpop()

Dshift()

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting parentheses causes no removal.

Using push() adds elements instead of removing.

pop() must be called as a function with parentheses to remove the last element.

4fill in blank

hard

Complete the code to remove the last element and print the updated array.

DSA Javascript

let colors = ['red', 'green', 'blue'];
colors.[1]();
console.log(colors);

Drag options to blanks, or click blank then click option'

Apop

Bpush

D.length - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using push() instead of pop().

Trying to print colors with an incorrect index.

pop() removes the last element; printing colors shows the updated array.

5fill in blank

hard

Fill both blanks to remove the last element, store it, and print both values.

DSA Javascript

let pets = ['dog', 'cat', 'rabbit'];
let removed = pets.[1]();
console.log(removed);
console.log(pets[2]);

Drag options to blanks, or click blank then click option'

Apop

C.length

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Using push() instead of pop().

Trying to print pets without length or index.

pop() removes and returns last element; printing removed shows it; printing pets.length shows updated length.

Practice

1. What does the pop() method do to an array in JavaScript?

easy

A. Returns the length of the array without modifying it

B. Removes the last element from the array and returns it

C. Adds a new element to the end of the array

D. Removes the first element from the array and returns it

Solution

1. Step 1: Understand the pop() method

   The pop() method removes the last element from an array and returns that element.

2. Step 2: Compare with other array methods

   Unlike shift() which removes the first element, pop() targets the end of the array.

3. Final Answer:

   Removes the last element from the array and returns it -> Option B

4. Quick Check:

   pop() removes last element [OK]

Hint: pop() always removes the last item from the array [OK]

Common Mistakes:

• Confusing pop() with shift() which removes the first element
• Thinking pop() adds elements instead of removing
• Assuming pop() returns the array length

2. Which of the following is the correct syntax to remove the last element from an array named arr?

easy

A. pop(arr);

B. arr.removeLast();

C. arr.pop();

D. arr.deleteLast();

Solution

1. Step 1: Identify the correct method for array end deletion

   JavaScript arrays use the pop() method to remove the last element.

2. Step 2: Check method call syntax

   The correct syntax is calling pop() directly on the array object: arr.pop();

3. Final Answer:

   arr.pop(); -> Option C

4. Quick Check:

   Use arr.pop() to remove last element [OK]

Hint: Use arr.pop() to remove last element [OK]

Common Mistakes:

• Using non-existent methods like removeLast() or deleteLast()
• Calling pop() as a standalone function instead of on the array
• Using incorrect syntax like pop(arr)

3. What will be the output of the following code?

const arr = [10, 20, 30, 40];
const removed = arr.pop();
console.log(arr);
console.log(removed);

medium

A. [10, 20, 30, 40] and 30

B. [10, 20, 30, 40] and 40

C. [10, 20, 30] and 30

D. [10, 20, 30] and 40

Solution

1. Step 1: Understand pop() effect on array

   The pop() method removes the last element (40) from arr and returns it.

2. Step 2: Check the console outputs

   After popping, arr becomes [10, 20, 30] and removed stores 40.

3. Final Answer:

   [10, 20, 30] and 40 -> Option D

4. Quick Check:

   pop() removes last element and returns it [OK]

Hint: pop() returns removed last element, array shrinks by one [OK]

Common Mistakes:

• Expecting pop() to remove first element
• Confusing returned value with new last element
• Thinking array remains unchanged after pop()

4. Identify the error in the following code that tries to remove the last element from an array:

const numbers = [1, 2, 3, 4];
numbers.pop(2);
console.log(numbers);

medium

A. pop() does not take any arguments; passing 2 is incorrect

B. pop() should be called as pop(numbers)

C. pop() removes the first element, so this code is wrong

D. pop() returns the new array, so console.log will be empty

Solution

1. Step 1: Check pop() method signature

   The pop() method does not accept any arguments; it always removes the last element.

2. Step 2: Analyze the code behavior

   Passing 2 as an argument does nothing and is incorrect usage, but JavaScript ignores it and still removes the last element.

3. Final Answer:

   pop() does not take any arguments; passing 2 is incorrect -> Option A

4. Quick Check:

   pop() takes no arguments [OK]

Hint: pop() never needs arguments to remove last element [OK]

Common Mistakes:

• Passing arguments to pop() expecting to remove specific elements
• Calling pop() as a standalone function
• Assuming pop() removes first element

5. Given the array let fruits = ['apple', 'banana', 'cherry', 'date'];, which code snippet correctly removes the last two elements and stores them in a new array removedFruits in the same order as they appeared in the original array?

hard

A. const removedFruits = fruits.splice(-2);

B. const removedFruits = fruits.pop(2);

C. const removedFruits = [fruits.pop(), fruits.pop()];

D. const removedFruits = fruits.shift(2);

Solution

1. Step 1: Understand pop() vs splice() for multiple deletions

   The pop() method removes only one element at a time. To remove multiple elements, splice() is used.

2. Step 2: Analyze each option

   const removedFruits = [fruits.pop(), fruits.pop()]; removes two elements but stores them in reverse order; const removedFruits = fruits.pop(2); is invalid as pop() takes no arguments; const removedFruits = fruits.splice(-2); correctly removes last two elements and returns them as an array in original order; const removedFruits = fruits.shift(2); uses shift() incorrectly.

3. Final Answer:

   const removedFruits = fruits.splice(-2); -> Option A

4. Quick Check:

   splice(-2) removes last two elements as array [OK]

Hint: Use splice(-2) to remove last two elements at once [OK]

Common Mistakes:

• Using pop() with arguments to remove multiple elements
• Confusing shift() with pop() for end deletion
• Expecting pop() to return an array of removed elements