Array Deletion at Beginning in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

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

DSA Typescript

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

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

Ashift

Bpop

Cslice

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

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

Using push() adds elements instead of removing.

The shift() method removes the first element from an array.

2fill in blank

medium

Complete the code to store and remove the first element from the array.

DSA Typescript

let arr = ['a', 'b', 'c'];
let first = arr.[1]();
console.log(first, arr);

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

Aslice

Bpop

Cshift

Dsplice

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop() returns last element, not first.

Using slice() does not modify the original array.

shift() removes the first element and returns it, so first stores that element.

3fill in blank

hard

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

DSA Typescript

let numbers = [10, 20, 30];
numbers.[1](0, 1);
console.log(numbers);

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

Apop

Bshift

Cslice

Dsplice

Attempts:

3 left

💡 Hint

Common Mistakes

Using shift(0) is invalid because shift takes no arguments.

Using pop(0) does not remove the first element.

splice(0, 1) removes one element starting at index 0, effectively removing the first element.

4fill in blank

hard

Fill both blanks to remove the first two elements from the array.

DSA Typescript

let fruits = ['apple', 'banana', 'cherry', 'date'];
fruits.[1]([2], 2);
console.log(fruits);

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

Asplice

Bslice

C0

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using slice does not modify the original array.

Using shift twice is possible but not efficient here.

splice(0, 2) removes two elements starting at index 0, removing the first two fruits.

5fill in blank

hard

Fill all three blanks to create a new array without the first element.

DSA Typescript

let colors = ['red', 'green', 'blue'];
let newColors = colors.[1]([2]);
console.log(newColors);

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

Asplice

Bslice

C1

Dshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using splice modifies the original array.

Using shift returns a single element, not an array.

slice(1) creates a new array starting from index 1, skipping the first element.

Practice

1. What does deleting the first element of an array using array.shift() do to the array?

easy

A. Removes the last element of the array

B. Removes the first element and shifts all other elements left

C. Deletes the entire array

D. Adds a new element at the beginning

Solution

1. Step 1: Understand shift() method

   The shift() method removes the first element of the array.

2. Step 2: Effect on array elements

   After removal, all other elements move one position to the left to fill the gap.

3. Final Answer:

   Removes the first element and shifts all other elements left -> Option B

4. Quick Check:

   shift() removes first element [OK]

Hint: Remember: shift() removes from start, pop() removes from end [OK]

Common Mistakes:

• Confusing shift() with pop()
• Thinking shift() deletes entire array
• Assuming shift() adds elements

2. Which of the following is the correct syntax to remove the first element from an array named nums in TypeScript?

easy

A. nums.shift()

B. nums.removeFirst()

C. nums.pop()

D. nums.delete(0)

Solution

1. Step 1: Identify the method to remove first element

   The correct method to remove the first element in TypeScript arrays is shift().

2. Step 2: Check other options

   pop() removes last element, removeFirst() and delete(0) are invalid methods.

3. Final Answer:

   nums.shift() -> Option A

4. Quick Check:

   Use shift() to remove first element [OK]

Hint: Use shift() to remove first element, pop() for last [OK]

Common Mistakes:

• Using pop() instead of shift()
• Using non-existent methods like removeFirst()
• Trying to delete with delete(0) which is invalid

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

let arr = [10, 20, 30, 40];
arr.shift();
console.log(arr);

medium

A. [40]

B. [10, 20, 30, 40]

C. [30, 40]

D. [20, 30, 40]

Solution

1. Step 1: Initial array and shift operation

   The array starts as [10, 20, 30, 40]. Calling shift() removes the first element 10.

2. Step 2: Resulting array after shift

   After removal, the array becomes [20, 30, 40].

3. Final Answer:

   [20, 30, 40] -> Option D

4. Quick Check:

   shift() removes first element, rest remain [OK]

Hint: shift() removes first element, so array starts from second element [OK]

Common Mistakes:

• Expecting original array unchanged
• Thinking shift() removes last element
• Confusing output with pop() effect

4. Consider this TypeScript code snippet:

let numbers = [5, 10, 15];
numbers.shift;
console.log(numbers);

What is the issue and how to fix it?

medium

A. Missing parentheses after shift; fix by using numbers.shift()

B. shift is not a valid method; use pop() instead

C. Array is empty; no fix needed

D. shift() removes last element; use unshift() instead

Solution

1. Step 1: Identify the method call mistake

   The code uses numbers.shift without parentheses, so the method is not called.

2. Step 2: Correct method call syntax

   Adding parentheses numbers.shift() calls the method and removes the first element.

3. Final Answer:

   Missing parentheses after shift; fix by using numbers.shift() -> Option A

4. Quick Check:

   Method calls need parentheses [OK]

Hint: Always add () to call methods like shift() [OK]

Common Mistakes:

• Forgetting parentheses on method calls
• Using pop() instead of shift() incorrectly
• Misunderstanding shift() removes first element

5. You have an array let fruits = ['apple', 'banana', 'cherry', 'date'];. You want to remove the first two fruits efficiently. Which code snippet correctly does this?

hard

A. fruits.shift(2);

B. fruits.pop(); fruits.pop();

C. fruits.splice(0, 2);

D. fruits.delete(0); fruits.delete(1);

Solution

1. Step 1: Understand removing multiple elements

   fruits.shift(2); fruits.shift(2); is incorrect: shift() takes no arguments (ignores 2) and removes only the first element.

2. Step 2: Using splice for efficient removal

   splice(0, 2) removes two elements starting at index 0 in one operation.

3. Step 3: Check other options

   pop() removes from end, delete() is invalid for arrays.

4. Final Answer:

   fruits.splice(0, 2); -> Option C

5. Quick Check:

   Use splice to remove multiple from start efficiently [OK]

Hint: Use splice(0, n) to remove n elements from start at once [OK]

Common Mistakes:

• Using shift(2) which only removes one element
• Using pop() which removes from end
• Using invalid delete() method