JavaScriptJavaScript · Bytes catalog

Screen JavaScript candidates on real starter repos

46 short JavaScript tasks, each shipping with a public test file and a language-specific runner. Candidates work in their own style; reviewers see how the code actually hangs together.

Starter
16
Standard
20
Advanced
10
Catalog
46 JavaScript bytes
Page 1 of 2
Access Badge
Featured
JavaScriptJavaScriptStandard~3h

Access Badge

Manage badge factory settings. When an access badge is issued, it starts out unnamed.

access-badge.js
access-badge.spec.js
babel.config.js
Open byte →
Alarm Beacon
JavaScriptJavaScript
Starter~2h
Alarm Beacon

Your task is to convert a signal code number into a string of beacon alert patterns.

alarm-beacon.js
alarm-beacon.spec.js
+1 more files
Alarm Chime
JavaScriptJavaScript
Starter~2h
Alarm Chime

Your task is to convert an alert code number into a string of alarm chime sounds.

alarm-chime.js
alarm-chime.spec.js
+1 more files
Alias Clusters
JavaScriptJavaScript
Starter~2h
Alias Clusters

In a user identity system, an alias cluster is a group of usernames that share exactly the same letters in a different arrangement. Two usernames belong to the same cluster if one can be formed by rearranging the letters of the other.

alias-clusters.js
alias-clusters.spec.js
+1 more files
Astral Pilot
JavaScriptJavaScript
Starter~2h
Astral Pilot

For an Astral Pilot simulation, each cadet begins by generating a pilot profile they can fly with.

astral-pilot.js
astral-pilot.spec.js
+1 more files
Badge Points
JavaScriptJavaScript
Standard~3h
Badge Points

Given a word, compute the badge points for that word. You'll need these:

babel.config.js
badge-points.js
+1 more files
Billing Cycle
JavaScriptJavaScript
Starter~2h
Billing Cycle

An internal billing system assigns sequential period numbers to billing cycles. Some periods are designated as extended — they receive an extra processing day for reconciliation.

babel.config.js
billing-cycle.js
+1 more files
Codec Bridge
JavaScriptJavaScript
Standard~3h
Codec Bridge

Convert an encoded payload, represented as a sequence of symbol values in one radix, to any other radix.

babel.config.js
codec-bridge.js
+1 more files
Cohort Roster
JavaScriptJavaScript
Standard~2h
Cohort Roster

You are building a roster system for a developer training academy. Participants are assigned to numbered cohorts based on their experience track. The program coordinator needs to view participants grouped by cohort, with each cohort's list sorted alphabeticall…

cohort-roster.js
cohort-roster.spec.js
+1 more files
Coin Combos
JavaScriptJavaScript
Advanced~4h
Coin Combos

Correctly determine the fewest number of coins needed to make an exact target amount from a supplied denomination list.

babel.config.js
coin-combos.js
+1 more files
Command Triplets
JavaScriptJavaScript
Starter~2h
Command Triplets

You are writing a decoder for a legacy industrial robot controller. The controller receives a continuous stream of 3-character instruction codes. Each triplet maps to a named operation. If a HALT code appears, execution stops immediately.

command-triplets.js
command-triplets.spec.js
+1 more files
Commit Jargon
JavaScriptJavaScript
Standard~3h
Commit Jargon

Implement a function that encodes plain English text into commit jargon. Your team uses an internal shorthand for obfuscating draft commit messages before they reach the shared log. The encoding follows a small set of deterministic rules applied word-by-word.

babel.config.js
commit-jargon.js
+1 more files
Config Drift
JavaScriptJavaScript
Starter~2h
Config Drift

You are working on a small internal tool that compares two configuration snapshots.

config-diff.js
config-diff.spec.js
+1 more files
Contact Cleanup
JavaScriptJavaScript
Starter~2h
Contact Cleanup

You are cleaning imported contact records before they are saved into a CRM. Each record includes a freeform phone field entered by a human, so the data can contain spaces, dots, parentheses, hyphens, and an optional leading country code of 1.

contact-cleanup.js
contact-cleanup.spec.js
+1 more files
Countdown Carol
JavaScriptJavaScript
Standard~3h
Countdown Carol

Output the lyrics to 'The Twelve Days of Christmas'. ``text On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.

babel.config.js
countdown-carol.js
+1 more files
Coverage Check
JavaScriptJavaScript
Starter~2h
Coverage Check

Determine if a text sample has full alphabet coverage. A sample with full coverage uses every letter of the alphabet at least once. The best-known example is: > The quick brown fox jumps over the lazy dog.

babel.config.js
coverage-check.js
+1 more files
Delivery Zones
JavaScriptJavaScript
Starter~2h
Delivery Zones

Classify a delivery drop-off location into the correct fee tier based on its distance from the warehouse.

babel.config.js
delivery-zones.js
+1 more files
Deploy Window
JavaScriptJavaScript
Advanced~4h
Deploy Window

Calculate the date of scheduled deployment windows. Your team follows a recurring deployment schedule: releases go out on a specific day of the week each month. In this exercise, you will take a description of a deployment window date, and return the actual de…

babel.config.js
deploy-window.js
+1 more files
Depot Shuttle
JavaScriptJavaScript
Starter~2h
Depot Shuttle

Your assignment is to write a depot shuttle navigator. A large distribution depot uses automated shuttles to move packages between loading bays. The depot's control system needs a program to verify shuttle movements before they are dispatched.

babel.config.js
depot-shuttle.js
+1 more files
Flag Sequence
JavaScriptJavaScript
Starter~2h
Flag Sequence

A maritime signal station transmits messages using a sequence of signal flags. A numeric transmission code determines which flags to raise and in what order.

flag-sequence.js
flag-sequence.spec.js
+1 more files
Grid Crossovers
JavaScriptJavaScript
Standard~3h
Grid Crossovers

Identify grid crossovers in an operations matrix. A grid crossover is a cell whose value is greater than or equal to every value in its row and less than or equal to every value in its column.

babel.config.js
grid-crossovers.js
+1 more files
Grid Hunt
JavaScriptJavaScript
Advanced~4h
Grid Hunt

In a grid hunt challenge you scan a rectangular field of characters to locate hidden target strings.

babel.config.js
grid-hunt.js
+1 more files
Hailstone Cascade
JavaScriptJavaScript
Starter~2h
Hailstone Cascade

Implement a steps function that computes how many cascade steps a hailstone particle takes to reach unit mass.

babel.config.js
hailstone-cascade.js
+1 more files
Help Desk Bot
JavaScriptJavaScript
Standard~3h
Help Desk Bot

Implement the response logic for a basic help-desk chatbot. The bot handles incoming support messages and replies with one of five canned responses based on the message content.

babel.config.js
help-desk-bot.js
+1 more files
Incident Chain
JavaScriptJavaScript
Standard~3h
Incident Chain

An internal post-mortem tool reconstructs incident chains. Each step in the chain describes an event and how it caused the next, building a cumulative narrative from the root cause forward.

incident-chain.js
incident-chain.spec.js
+1 more files
Invoice Words
JavaScriptJavaScript
Standard~3h
Invoice Words

An invoicing system needs to print amounts in words on official documents. Given an integer from 0 to 999,999,999,999, return its English representation.

babel.config.js
invoice-words.js
+1 more files
Log Scanner
JavaScriptJavaScript
Standard~3h
Log Scanner

Your team needs a lightweight log scanning tool. Given one or more server log files, scan for lines that match a user-provided pattern and print the results. Lines should appear in the order they are found, starting with the first match in the first file.

babel.config.js
log-scanner.js
+1 more files
Meter Reader
JavaScriptJavaScript
Standard~3h
Meter Reader

Read the digits shown on an industrial meter's segment display. Each digit is rendered as a 3-column × 4-row pattern of pipes (|), underscores (_), and spaces. Parse these patterns and return the corresponding numeric string.

babel.config.js
meter-reader.js
+1 more files
Metric Network
JavaScriptJavaScript
Advanced~4h
Metric Network

Implement a metric dependency network. In monitoring systems, metrics often depend on other metrics. A source metric is collected directly (e.g. CPU usage), while a derived metric is computed from one or more upstream metrics (e.g.

babel.config.js
metric-network.js
+1 more files
Parcel Verifier
JavaScriptJavaScript
Standard~3h
Parcel Verifier

The parcel reference checksum process is used to validate operational parcel identifiers. These normally contain dashes and look like: 3-598-21508-8

babel.config.js
package.json
+1 more files