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Official agent skill

Compare Array Bundle Size

by PostHog in PostHog/posthog-js

Quickly compare the posthog-js array.js bundle size in the current working tree against a git baseline using the repository's esbuild proxy.

OfficialCustom licenceAuto-check passedFrontend & Design

Install Compare Array Bundle Size

skills CLI
$ npx skills add PostHog/posthog-js --skill compare-array-bundle-size -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install PostHog/posthog-js compare-array-bundle-size --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/PostHog/posthog-js.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/compare-array-bundle-size .claude/skills/compare-array-bundle-size && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
compare-array-bundle-size
GitHub stars
613
Token cost
~599 tokens
SKILL.md length
277 words
Files
1
Skills in repo
3
Repo updated
First seen
Licence
Custom licence

At a glance

Quickly compare the posthog-js array.js bundle size in the current working tree against a git baseline using the repository's esbuild proxy.

  • Works in 4 steps: Use the baseline named by the user. If… → From the repository root, run → Report → …
  • Asked about array.js size
  • SKILL.md covers Workflow, Interpretation and Validation and troubleshooting
  • Calls pnpm

What it does

Compare Array Bundle Size is an agent skill from PostHog/posthog-js, published by the product's own GitHub organization. Quickly compare the posthog-js array.js bundle size in the current working tree against a git baseline using the repository's esbuild proxy. Use when asked about array.js size, bundle-size percentage changes, whether browser SDK changes increased the bundle, or for a fast size check that should not run the production Rollup build.

Its SKILL.md is about 600 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: Requires a posthog-js checkout with dependencies installed.

It sits in Frontend & Design, covering Web performance. It works with PostHog, Git, TypeScript and npm. The repository describes itself as: Send usage data from your web app or site to PostHog, with autocapture.

When your agent uses it

  • Asked about array.js size
  • Bundle-size percentage changes
  • Whether browser SDK changes increased the bundle
  • For a fast size check that should not run the production Rollup build

Example prompts

  • “/compare-array-bundle-size”

Requirements

  • Compatibility (from SKILL.md): Requires a posthog-js checkout with dependencies installed.

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

  1. Use the baseline named by the user. If none is given, let the script default to origin/main and then main.
  2. From the repository root, run
  3. Report
  4. Lead with the percentage most relevant to the user's question. If they did not specify one, lead with minified and include the compressed…

What it can do on your machine

Read from SKILL.md and the folder at commit e75146a. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • pnpm

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use pnpm, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

  • Compatibility

    Requires a posthog-js checkout with dependencies installed.

    From compatibility in the SKILL.md frontmatter.

Context cost

Compare Array Bundle Size loads about 599 tokens when it runs. Until then it costs about 90 tokens; SKILL.md has 277 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~90
When it runs · the whole SKILL.md, loaded when a task matches
~599

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 277 words (~599 tokens).

“Use the repository's fast comparison command. Do not run TypeScript compilation, Terser, Rollup, Turbo, or the full build unless the user separately requests production bundle numbers.”

— opening of SKILL.md by PostHog, Custom licence
name
compare-array-bundle-size
compatibility
Requires a posthog-js checkout with dependencies installed.

Read the full SKILL.md on GitHub

Files

Just SKILL.md in .agents/skills/compare-array-bundle-size of PostHog/posthog-js.

Open the folder on GitHubat commit e75146a

Compare with similar skills

Compare Array Bundle Size next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Compare Array Bundle Size compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Compare Array Bundle Size this skillPostHog/posthog-js613—~599Automated safety check: PassCustom licence
Logseq Plugin SDKlogseq/logseq45k—~2.3kAutomated safety check: PassAGPL-3.0
Markbind Typescript MigrationMarkBind/markbind158—~2kAutomated safety check: PassMIT
Reduce Bundle Sizekcsujeet/ilamy-calendar351—~2.9kAutomated safety check: PassMIT
Release TS SDKaptos-labs/aptos-ts-sdk116—~864Automated safety check: PassCustom licence
Typescriptccusage/ccusage19k—~696Automated safety check: PassCustom licence

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Works with

Categories

Questions about Compare Array Bundle Size

What does Compare Array Bundle Size do?

Quickly compare the posthog-js array.js bundle size in the current working tree against a git baseline using the repository's esbuild proxy. Compare Array Bundle Size is an agent skill from PostHog/posthog-js, published by the product's own GitHub organization.js bundle size in the current working tree against a git baseline using the repository's esbuild proxy.

When should I use Compare Array Bundle Size?

Compare Array Bundle Size fits situations like: asked about array.js size; bundle-size percentage changes; whether browser SDK changes increased the bundle; for a fast size check that should not run the production Rollup build.

How do I install Compare Array Bundle Size in Claude Code?

Run `npx skills add PostHog/posthog-js --skill compare-array-bundle-size -a claude-code`. Or copy the skill folder (.agents/skills/compare-array-bundle-size in PostHog/posthog-js) into .claude/skills/compare-array-bundle-size in your project. Claude Code loads it when a task matches its description.

How do I install Compare Array Bundle Size in Codex?

Run `npx skills add PostHog/posthog-js --skill compare-array-bundle-size -a codex`. Or copy the skill folder (.agents/skills/compare-array-bundle-size in PostHog/posthog-js) into .agents/skills/compare-array-bundle-size in your project. Codex loads it when a task matches its description.

Can I use Compare Array Bundle Size in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add PostHog/posthog-js --skill compare-array-bundle-size -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/compare-array-bundle-size, .gemini/skills/compare-array-bundle-size, .github/skills/compare-array-bundle-size and .opencode/skills/compare-array-bundle-size in your project.

What does Compare Array Bundle Size need to run?

Going by SKILL.md and its folder, Compare Array Bundle Size needs the command-line tools its instructions call (pnpm). Compatibility (from SKILL.md): Requires a posthog-js checkout with dependencies installed..

Does Compare Array Bundle Size access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Compare Array Bundle Size safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Compare Array Bundle Size use?

Compare Array Bundle Size has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.

How many tokens does Compare Array Bundle Size use?

About 599 tokens (SKILL.md is roughly 2.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Compare Array Bundle Size?

Skills that share tags, products or a category with Compare Array Bundle Size: Logseq Plugin SDK (logseq/logseq, 45k stars), Markbind Typescript Migration (MarkBind/markbind, 158 stars), Reduce Bundle Size (kcsujeet/ilamy-calendar, 351 stars) and Release TS SDK (aptos-labs/aptos-ts-sdk, 116 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Compare Array Bundle Size?

PostHog (a GitHub organization, an official publisher) maintains it in PostHog/posthog-js, which has 613 GitHub stars. The repository holds 3 skills in this directory. The repository was last updated on October 7, 2026.

Source: PostHog/posthog-js on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.