Surya JS Journey

Learn JavaScript through concepts, code, and guided practice.

A focused workspace for concept study, interactive examples, visual explanations, and challenge solving.

ChallengeBeginner7 min

Complete an arrow callback

Use an arrow function to transform a list of numbers into doubled values.

Finish the arrow callback so the output becomes `2,4,6`. Do not rewrite the surrounding structure.

Challenge Brief

Solve the exercise by editing the starter code and running it in the panel. Compare your result against the expected outcome, then refine your solution until the behavior matches.

  1. 1. Read the prompt carefully and identify the missing behavior.
  2. 2. Update only the parts of the starter code needed to solve it.
  3. 3. Run the code and compare actual output with the expected result.

Hints

  • The callback should return each item multiplied by `2`.
  • A concise arrow body can return an expression directly.
  • The final log joins the result for you.

Related Concepts

Arrow Functions

Arrow functions provide a shorter function syntax and handle `this` differently from regular functions.

Arrays and Methods

Arrays hold ordered collections of values, and their built-in methods make transformation and iteration much easier.

Challenge Workspace

arrow-transform.js

Edit the code, run it in the browser, and inspect the console output below. Reset restores the original snippet for this page.

Editor

6 lines

Output

0 entries

Mode

challenge

Workspace Notes

Changes stay local until you run the code. Reset restores the original snippet immediately for another pass.

Live editing

Safe to change before every run.

Fast reset

Return to the original starter instantly.

arrow-transform.js
6 linesMonaco Editor
Loading...

Editor Actions

Run your solution and compare the result with the expected challenge output.

Console0 entries

Run the code to see output here.

Challenge Result

Run the code to check whether your solution matches the expected outcome.

Expected Output

2,4,6

Continue in Playground

Open this starter code in the shared playground if you want a focused space for experimenting outside the challenge page.

Open in Playground