Repository Analysis

leonardomso/33-js-concepts

📜 33 JavaScript concepts every developer should know.

2.5 Likely human-written View on GitHub

Analysis Overview

This report presents the forensic synthetic code analysis of leonardomso/33-js-concepts, a JavaScript project with 66,484 GitHub stars. SynthScan v2.0 examined 60,861 lines of code across 93 source files, recording 83 pattern matches distributed across 6 syntactic categories. The overall adjusted score of 2.5 places this repository in the Likely human-written band.

The scanner applied 160+ deterministic lexical heuristics, multi-line block detectors, abstract syntax tree depth profilers, and a cross-file Jaccard similarity matrix to construct a statistically normalised synthetic code estimate. All matches are individually weighted by severity coefficient and contextual multiplier before summation, and the resulting headline score is temporally discounted to account for the repository's development history relative to the commercial emergence of large language model coding tooling (November 2022 onward).

2.5
Adjusted Score
2.5
Raw Score
100%
Time Factor
2026-06-06
Last Push
66.5K
Stars
JavaScript
Language
60.9K
Lines of Code
93
Files
83
Pattern Hits
2026-07-14
Scan Date
0.00
HC Hit Rate

What These Metrics Mean

Adjusted Score
Primary synthetic code indicator. Raw score normalised per 1,000 lines of code and multiplied by the temporal discount factor. This is the definitive comparative metric — use it to rank repositories by AI authorship density.
Raw Score
The unmodified sum of all severity-weighted, context-multiplied pattern match scores before temporal discounting. Reflects the absolute signal strength independent of when the repository was last active.
Time Factor
The temporal discount multiplier (0–100%) applied to the raw score. Repositories last updated before ChatGPT's launch (Nov 2022) receive a 5% factor. Full signal is only assigned to repositories active in the post-adoption era (Jan 2024+).
Pattern Hits
Total count of individual pattern matches across all files and categories. A high hit count with a low score may indicate a very large codebase with isolated AI snippets; a low count with a high score indicates dense, concentrated AI signatures.
HC Hit Rate
High+Critical pattern hits per file, averaged across the repository. This orthogonal signal catches repositories where a few files are densely packed with high-severity AI tells — a strong indicator even when the normalised score appears moderate due to codebase size.
Lines of Code / Files
Total lines and files analysed. The scanner examines 94 file extensions. These denominators are used to normalise the score, enabling fair comparison between repositories of vastly different sizes.

Score History

This chart maps the temporal evolution of the adjusted synthetic code score across successive scan runs. An upward trajectory indicates ongoing incorporation of AI-generated code or expanding LLM-assisted scaffolding; a stable or declining trajectory may reflect active human refactoring, code removal, or the adoption of stricter authorship policies. The dashed secondary line (right axis) independently tracks total raw pattern hit count, which can diverge from the normalised score when codebase size changes significantly between scans.

Severity Breakdown

Classifies detected patterns by their diagnostic confidence and structural impact. CRITICAL patterns (coefficient 10) represent definitive synthetic signatures — hallucinated imports, explicit LLM attribution metadata — virtually never produced by human authors. HIGH (5) indicates strong structural tells such as cross-file repetition or cross-linguistic idioms. MEDIUM (2) covers recognisable conversational padding and AI-specific vocabulary. LOW (1) captures subtle indicators like tautological comments and generic boilerplate that require density to carry independent signal.

CRITICAL 0HIGH 0MEDIUM 1LOW 82

Directory Score Breakdown

This horizontal bar chart decomposes the repository's raw synthetic code score by top-level directory, allowing you to pinpoint precisely which modules or components carry the highest AI authorship density. Directories with disproportionately high scores relative to their size warrant targeted manual review: concentrated AI signatures often trace back to mass-generated configuration layers, auto-ported test suites, LLM-scaffolded boilerplate classes, or entire subsystems authored under heavy copilot assistance. Use this view to prioritise your human code-review effort.

Pattern Findings

The scanner identified 83 distinct pattern matches across 6 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a statistically significant AI authorship indicator. Expand any category row to inspect the individual file paths, line numbers, code snippets, and the lexical context (CODE, COMMENT, or STRING) in which each match was detected.

Reading the findings table: The Severity column indicates the diagnostic confidence level (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — comment-context matches receive a ×1.5 weight because LLMs systematically over-annotate. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier as dense clusters constitute far stronger evidence of synthetic authorship than isolated hits.

Structural Annotation Overuse48 hits · 100 pts
SeverityFileLineSnippetContext
LOW.opencode/skill/write-concept/SKILL.md253// Step 1: Do thisCOMMENT
LOW.opencode/skill/write-concept/SKILL.md256// Step 2: Then thisCOMMENT
LOW.opencode/skill/write-concept/SKILL.md259// Step 3: FinallyCOMMENT
LOW.opencode/skill/write-concept/SKILL.md1062// Step 1: fetch() returns a Promise that resolves to a Response objectCOMMENT
LOW.opencode/skill/write-concept/SKILL.md1065// Step 2: When the response arrives, we get a Response objectCOMMENT
LOW.opencode/skill/write-concept/SKILL.md1069 // Step 3: The body is a stream, we need to parse itCOMMENT
LOW.opencode/skill/write-concept/SKILL.md1073 // Step 4: Now we have the actual dataCOMMENT
LOW.opencode/skill/concept-workflow/SKILL.md383### Step 1: InitializeCOMMENT
LOW.opencode/skill/concept-workflow/SKILL.md393### Step 2: Execute Each PhaseCOMMENT
LOW.opencode/skill/concept-workflow/SKILL.md417### Step 3: Final ReportCOMMENT
LOW.opencode/skill/seo-review/SKILL.md33### Step 1: Identify Target KeywordsCOMMENT
LOW.opencode/skill/seo-review/SKILL.md50### Step 2: On-Page SEO AuditCOMMENT
LOW.opencode/skill/seo-review/SKILL.md54### Step 3: Featured Snippet OptimizationCOMMENT
LOW.opencode/skill/seo-review/SKILL.md58### Step 4: Internal Linking AuditCOMMENT
LOW.opencode/skill/seo-review/SKILL.md62### Step 5: Generate ReportCOMMENT
LOW.opencode/skill/resource-curator/SKILL.md293### Step 1: Check Each LinkCOMMENT
LOW.opencode/skill/resource-curator/SKILL.md308### Step 2: Content VerificationCOMMENT
LOW.opencode/skill/resource-curator/SKILL.md317### Step 3: Description ReviewCOMMENT
LOW.opencode/skill/resource-curator/SKILL.md326### Step 4: Gap AnalysisCOMMENT
LOW…amentals/equality-operators/equality-operators.test.js146 // Step 1: Evaluate ![]COMMENT
LOW…amentals/equality-operators/equality-operators.test.js151 // Step 2: Now we have [] == falseCOMMENT
LOW…amentals/equality-operators/equality-operators.test.js155 // Step 3: Object → PrimitiveCOMMENT
LOW…amentals/equality-operators/equality-operators.test.js159 // Step 4: String → NumberCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1222 // Step 1: Create empty objectCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1225 // Step 2: Link prototype if it's an objectCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1230 // Step 3: Bind this and executeCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1233 // Step 4: Return object (unless constructor returns a non-primitive)COMMENT
LOW…rogramming/map-reduce-filter/map-reduce-filter.test.js770 // Step 1: Get boolean results for each elementCOMMENT
LOW…rogramming/map-reduce-filter/map-reduce-filter.test.js773 // Step 2: Filter using the boolean resultsCOMMENT
LOW.claude/skills/write-concept/SKILL.md253// Step 1: Do thisCOMMENT
LOW.claude/skills/write-concept/SKILL.md256// Step 2: Then thisCOMMENT
LOW.claude/skills/write-concept/SKILL.md259// Step 3: FinallyCOMMENT
LOW.claude/skills/write-concept/SKILL.md1062// Step 1: fetch() returns a Promise that resolves to a Response objectCOMMENT
LOW.claude/skills/write-concept/SKILL.md1065// Step 2: When the response arrives, we get a Response objectCOMMENT
LOW.claude/skills/write-concept/SKILL.md1069 // Step 3: The body is a stream, we need to parse itCOMMENT
LOW.claude/skills/write-concept/SKILL.md1073 // Step 4: Now we have the actual dataCOMMENT
LOW.claude/skills/concept-workflow/SKILL.md383### Step 1: InitializeCOMMENT
LOW.claude/skills/concept-workflow/SKILL.md393### Step 2: Execute Each PhaseCOMMENT
LOW.claude/skills/concept-workflow/SKILL.md417### Step 3: Final ReportCOMMENT
LOW.claude/skills/seo-review/SKILL.md33### Step 1: Identify Target KeywordsCOMMENT
LOW.claude/skills/seo-review/SKILL.md50### Step 2: On-Page SEO AuditCOMMENT
LOW.claude/skills/seo-review/SKILL.md54### Step 3: Featured Snippet OptimizationCOMMENT
LOW.claude/skills/seo-review/SKILL.md58### Step 4: Internal Linking AuditCOMMENT
LOW.claude/skills/seo-review/SKILL.md62### Step 5: Generate ReportCOMMENT
LOW.claude/skills/resource-curator/SKILL.md293### Step 1: Check Each LinkCOMMENT
LOW.claude/skills/resource-curator/SKILL.md308### Step 2: Content VerificationCOMMENT
LOW.claude/skills/resource-curator/SKILL.md317### Step 3: Description ReviewCOMMENT
LOW.claude/skills/resource-curator/SKILL.md326### Step 4: Gap AnalysisCOMMENT
Verbosity Indicators10 hits · 22 pts
SeverityFileLineSnippetContext
LOW…amentals/equality-operators/equality-operators.test.js146 // Step 1: Evaluate ![]COMMENT
LOW…amentals/equality-operators/equality-operators.test.js151 // Step 2: Now we have [] == falseCOMMENT
LOW…amentals/equality-operators/equality-operators.test.js155 // Step 3: Object → PrimitiveCOMMENT
LOW…amentals/equality-operators/equality-operators.test.js159 // Step 4: String → NumberCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1222 // Step 1: Create empty objectCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1225 // Step 2: Link prototype if it's an objectCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1230 // Step 3: Bind this and executeCOMMENT
LOW…nted/this-call-apply-bind/this-call-apply-bind.test.js1233 // Step 4: Return object (unless constructor returns a non-primitive)COMMENT
LOW…rogramming/map-reduce-filter/map-reduce-filter.test.js770 // Step 1: Get boolean results for each elementCOMMENT
LOW…rogramming/map-reduce-filter/map-reduce-filter.test.js773 // Step 2: Filter using the boolean resultsCOMMENT
Overly Generic Function Names12 hits · 12 pts
SeverityFileLineSnippetContext
LOW…amentals/scope-and-closures/scope-and-closures.test.js26 function processData() {CODE
LOW…amentals/primitives-objects/primitives-objects.test.js775 function processData(data) {CODE
LOW…jects-properties/object-methods/object-methods.test.js524 function processData(data) {CODE
LOW…erformance/memory-management/memory-management.test.js220 function processData() {CODE
LOW…erformance/memory-management/memory-management.test.js314 function getData(obj) {CODE
LOW…erformance/memory-management/memory-management.test.js452 function processData() {CODE
LOW…formance/garbage-collection/garbage-collection.test.js141 function processData() {CODE
LOWtests/async-javascript/callbacks/callbacks.test.js832 function getData(callback) {CODE
LOWtests/async-javascript/callbacks/callbacks.test.js839 function processData(data, callback) {CODE
LOWtests/async-javascript/callbacks/callbacks.test.js1044 function getData(key, callback) {CODE
LOWtests/async-javascript/callbacks/callbacks.test.js1088 function getData(key, callback) {CODE
LOW…ts/functions-execution/async-await/async-await.test.js854 async function getData() {CODE
Fake / Example Data8 hits · 10 pts
SeverityFileLineSnippetContext
LOW…cts-properties/weakmap-weakset/weakmap-weakset.test.js254 expect(getFullName(person)).toBe('John Doe')CODE
LOW…cts-properties/weakmap-weakset/weakmap-weakset.test.js257 expect(getFullName(person)).toBe('John Doe')CODE
LOW…topics/regular-expressions/regular-expressions.test.js231 const match = '555-1234'.match(pattern)CODE
LOW…topics/regular-expressions/regular-expressions.test.js232 expect(match[0]).toBe('555-1234')CODE
LOW…topics/regular-expressions/regular-expressions.test.js239 const match = '555-1234'.match(pattern)CODE
LOW…topics/regular-expressions/regular-expressions.test.js291 expect(email.test('user@example.com')).toBe(true)CODE
LOW…/functions-execution/iife-modules/iife-modules.test.js741 authModule.login('user@example.com')CODE
LOW…/functions-execution/iife-modules/iife-modules.test.js742 expect(authModule.getCurrentUser().email).toBe('user@example.com')CODE
Over-Commented Block4 hits · 4 pts
SeverityFileLineSnippetContext
LOWtests/beyond/browser-storage/cookies/cookies.test.js1import { describe, it, expect } from 'vitest'COMMENT
LOW…/advanced-topics/error-handling/error-handling.test.js541 // The following patterns from the concept page are browser-specificCOMMENT
LOWtests/async-javascript/callbacks/callbacks.test.js1241 setTimeout(() => output.push('D'), 0)COMMENT
LOWdocs/robots.txt1# Belt-and-suspenders robots.txt for 33jsconcepts.comCOMMENT
AI Slop Vocabulary1 hit · 3 pts
SeverityFileLineSnippetContext
MEDIUM…ged-template-literals/tagged-template-literals.test.js330 // More robust key extraction - handles the actual string splittingCOMMENT