Adding and removing properties in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a new property age with value 25 to the object.

Javascript

const person = { name: 'Alice' };
person.[1] = 25;

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

Aage

Blength

Cpush

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using array methods like push or pop on an object.

Trying to assign a value to a method name.

To add a new property to an object, use dot notation with the property name. Here, person.age = 25; adds the property age.

2fill in blank

medium

Complete the code to remove the property color from the object.

Javascript

const car = { brand: 'Toyota', color: 'red' };
delete car.[1];

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

Acolor

Bbrand

Clength

Dmodel

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to assign null or undefined instead of deleting.

Deleting a property that does not exist.

The delete operator removes a property from an object. Here, delete car.color; removes the color property.

3fill in blank

hard

Fix the error in the code to correctly add a property height with value 180.

Javascript

const obj = {};
obj[1] = 180;

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

A[height]

B.height

C['height']

Dheight

Attempts:

3 left

💡 Hint

Common Mistakes

Using brackets without quotes for property names.

Trying to assign a value without dot or bracket notation.

To add a property using dot notation, use a dot followed by the property name without quotes or brackets. So, obj.height = 180; works correctly.

4fill in blank

hard

Fill both blanks to add a property score with value 100 and then remove it.

Javascript

const game = {};
game[1] = 100;
delete game[2];

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

A.score

B['score']

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing dot and bracket notation incorrectly.

Forgetting quotes in bracket notation.

You can add a property using dot notation: game.score = 100;. To delete it using bracket notation: delete game['score'];.

5fill in blank

hard

Fill all three blanks to add a property name with value 'Bob', update it to 'Robert', and then remove it.

Javascript

const user = {};
user[1] = 'Bob';
user[2] = 'Robert';
delete user[3];

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

A.name

B['name']

Attempts:

3 left

💡 Hint

Common Mistakes

Using bracket notation without quotes.

Trying to delete with dot notation without quotes.

Add and update the property using dot notation: user.name = 'Bob'; user.name = 'Robert';. Remove it using bracket notation: delete user['name'];.