map operator for transformation in Angular - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the map operator from RxJS.

Angular

import { [1] } from 'rxjs/operators';

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

Amap

Btap

Cfilter

DswitchMap

Attempts:

3 left

💡 Hint

Common Mistakes

Importing the wrong operator like filter or tap instead of map.

Forgetting to import from 'rxjs/operators'.

The map operator is imported from rxjs/operators to transform emitted values.

2fill in blank

medium

Complete the code to transform each emitted number by doubling it using map.

Angular

numbers$.pipe([1](x => x * 2)).subscribe(console.log);

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

Afilter

Bmap

Ctap

Dreduce

Attempts:

3 left

💡 Hint

Common Mistakes

Using filter instead of map, which filters values instead of transforming.

Using tap which only performs side effects without changing values.

The map operator applies a function to each emitted value, here doubling each number.

3fill in blank

hard

Fix the error in the code to correctly transform emitted strings to uppercase using map.

Angular

source$.pipe([1](str => str.toUpperCase())).subscribe(console.log);

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

Afilter

BconcatMap

Ctap

Dmap

Attempts:

3 left

💡 Hint

Common Mistakes

Using filter which filters values instead of transforming.

Using tap which does not change the emitted values.

The map operator transforms each emitted string to uppercase.

4fill in blank

hard

Fill both blanks to create a map operator that adds 10 to each emitted number and then filters out numbers less than 20.

Angular

source$.pipe([1](x => x + 10), [2](x => x >= 20)).subscribe(console.log);

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

Amap

Bfilter

Ctap

Dreduce

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of map and filter.

Using tap instead of filter for filtering.

First, map adds 10 to each number. Then, filter removes numbers less than 20.

5fill in blank

hard

Fill all three blanks to create a map operator that converts strings to lowercase, trims whitespace, and then filters out empty strings.

Angular

source$.pipe([1](str => str.toLowerCase()), [2](str => str.trim()), [3](str => str !== '')).subscribe(console.log);

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

Amap

Cfilter

Dtap

Attempts:

3 left

💡 Hint

Common Mistakes

Using tap instead of map for transformations.

Using map instead of filter to remove empty strings.

The first two map operators transform the strings to lowercase and trim whitespace. The filter removes empty strings.