Iterating over objects in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to loop over the keys of the object.

Javascript

const obj = {a: 1, b: 2, c: 3};
for (const [1] in obj) {
  console.log([1]);
}

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

Aitem

Bvalue

Ckey

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'value' instead of 'key' in the for...in loop variable.

Trying to use 'for...of' directly on an object.

The 'for...in' loop iterates over the keys of the object, so the variable should be named 'key' to represent each key.

2fill in blank

medium

Complete the code to get the values of the object using Object.values().

Javascript

const obj = {x: 10, y: 20};
const values = Object.[1](obj);
console.log(values);

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

Avalues

Bkeys

Centries

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using Object.keys() instead of Object.values().

Trying to call a non-existent method like Object.get().

Object.values(obj) returns an array of the object's values.

3fill in blank

hard

Fix the error in the code to correctly iterate over object entries.

Javascript

const obj = {a: 1, b: 2};
for (const [key, [1]] of Object.entries(obj)) {
  console.log(key, [1]);
}

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

Aentry

Bitem

Cindex

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'item' or 'index' which do not represent the value.

Trying to destructure incorrectly.

Object.entries(obj) returns [key, value] pairs, so the second variable should be 'value'.

4fill in blank

hard

Fill both blanks to create a new object with keys in uppercase and values doubled.

Javascript

const obj = {a: 1, b: 2};
const newObj = Object.fromEntries(
  Object.entries(obj).map(([[1], [2]]) => [[1].toUpperCase(), [2] * 2])
);
console.log(newObj);

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

Akey

Bvalue

Citem

Dentry

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping key and value in destructuring.

Using unclear variable names like 'item' or 'entry'.

When destructuring entries, the first element is the key and the second is the value.

5fill in blank

hard

Fill all three blanks to filter object entries with values greater than 10 and create a new object.

Javascript

const obj = {a: 5, b: 15, c: 25};
const filteredObj = Object.fromEntries(
  Object.entries(obj)
    .filter(([[1], [2]]) => [2] [3] 10)
);
console.log(filteredObj);

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

Akey

Bvalue

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the filter condition.

Swapping key and value in destructuring.

Destructure entries as [key, value], then filter where value > 10.