SEASON 1: ZERO-DAY PROTOCOL LIVE // 20 ANOMALIES ACTIVE

HUNT THE BUG.
BEAT THE CLOCK.

The premier competitive debugging arena. Fix real broken JavaScript algorithms in timed 1v1 PvP combat, preserve streak multipliers, climb the Elo ladder, and claim global engineer supremacy.

ENTER THE ARENA 1V1 COMBAT DUELS DAILY BUG BOUNTY
anomaly_detector.js
TELEMETRY SIMULATOR
// BUGGY SOURCE (LINE 4 FAILED) 
function findAnomaly(records) {
  let count = 0;
  for (let i = 0; i <= records.length; i++) {
    if (records[i].isCorrupt) count++; // TypeError!  }
  return count;
}
// YOUR REPAIR (STATIC PASSED) 
function findAnomaly(records) {
  let count = 0;
  for (let i = 0; i < records.length; i++) {
    if (records[i]?.isCorrupt) count++; // Fixed!  }
  return count;
}
ALL 3 TEST ASSERTIONS PASSED (14ms)
+250 XP AWARDED
20
PRODUCTION BUGS
0
ANOMALIES ELIMINATED
0
1V1 DUELS RESOLVED
145,000
TOTAL XP AWARDED
10
ACTIVE OPERATIVES
// OPERATIONAL PROTOCOL //

HOW THE ARENA WORKS

Three high-intensity phases designed to test your diagnostic speed and precision coding.

01

INSPECT ANOMALY

Read real JavaScript source files riddled with off-by-one errors, memory leaks, race conditions, closures, and async edge cases.

02

PATCH & VERIFY

Write and format your patch in the web-based CodeMirror editor. Execute real-time static test suites with instant assertion telemetry.

03

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BUG OF THE DAY EASY

Off-By-One Array Bound

An array summation utility is throwing undefined errors or NaN because its loop boundary traverses past the final index. Fix the loop guard to properly sum array elements without i...

DAILY BOUNTY VALUE
+100
EXPERIENCE POINTS
+1 Day Streak Bonus
// CHALLENGE HALL SPOTLIGHT //

FEATURED ANOMALIES

VIEW ALL 20 CHALLENGES
EASY
+100 XP

Off-By-One Array Bound

An array summation utility is throwing undefined errors or NaN because its loop boundary traverses past the final index. Fix the loop guard to properly sum array elements without indexing out of bounds.

5m limit 0 Solves JAVASCRIPT
HUNT BUG →
EASY
+100 XP

Strict Equality Type Coercion

A boolean status check function is inadvertently accepting string falsy values due to loose type comparison. Refactor the equality check so that only strict boolean true returns valid.

5m limit 0 Solves JAVASCRIPT
HUNT BUG →
EASY
+100 XP

Mutable Default Argument

A tag registration function allows caller overrides, but when items array is omitted, it fails to initialize a fresh array if null is supplied. Fix the function so items defaults to a clean array when not provided or null.

5m limit 0 Solves JAVASCRIPT
HUNT BUG →

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