Agent skill

Javascript Actions

Create, call and drop JavaScript actions — client-side logic called from nanoflows, not microflows.

Apache-2.0Auto-check passed

Install Javascript Actions

skills CLI

$ npx skills add mendixlabs/mxcli --skill javascript-actions -a claude-code

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

GitHub CLI

$ gh skill install mendixlabs/mxcli javascript-actions --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/mendixlabs/mxcli.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/mendix/javascript-actions .claude/skills/javascript-actions && 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/

Paste into Claude Code

Install the "javascript-actions" agent skill from https://github.com/mendixlabs/mxcli/tree/main/.claude/skills/mendix/javascript-actions into .claude/skills/javascript-actions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "javascript-actions", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/mendixlabs/mxcli/tree/main/.claude/skills/mendix/javascript-actions

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add mendixlabs/mxcli --skill javascript-actions -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install mendixlabs/mxcli javascript-actions --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mendixlabs/mxcli.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/mendix/javascript-actions .agents/skills/javascript-actions && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "javascript-actions" agent skill from https://github.com/mendixlabs/mxcli/tree/main/.claude/skills/mendix/javascript-actions into .agents/skills/javascript-actions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "javascript-actions", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add mendixlabs/mxcli --skill javascript-actions -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install mendixlabs/mxcli javascript-actions --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mendixlabs/mxcli.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/mendix/javascript-actions .cursor/skills/javascript-actions && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "javascript-actions" agent skill from https://github.com/mendixlabs/mxcli/tree/main/.claude/skills/mendix/javascript-actions into .cursor/skills/javascript-actions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "javascript-actions", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/mendixlabs/mxcli.git --path .claude/skills/mendix/javascript-actions

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add mendixlabs/mxcli --skill javascript-actions -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install mendixlabs/mxcli javascript-actions --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mendixlabs/mxcli.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/mendix/javascript-actions .gemini/skills/javascript-actions && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "javascript-actions" agent skill from https://github.com/mendixlabs/mxcli/tree/main/.claude/skills/mendix/javascript-actions into .gemini/skills/javascript-actions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "javascript-actions", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install mendixlabs/mxcli javascript-actions

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add mendixlabs/mxcli --skill javascript-actions -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/mendixlabs/mxcli.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/mendix/javascript-actions .github/skills/javascript-actions && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "javascript-actions" agent skill from https://github.com/mendixlabs/mxcli/tree/main/.claude/skills/mendix/javascript-actions into .github/skills/javascript-actions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "javascript-actions", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add mendixlabs/mxcli --skill javascript-actions -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install mendixlabs/mxcli javascript-actions --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mendixlabs/mxcli.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/mendix/javascript-actions .opencode/skills/javascript-actions && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "javascript-actions" agent skill from https://github.com/mendixlabs/mxcli/tree/main/.claude/skills/mendix/javascript-actions into .opencode/skills/javascript-actions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "javascript-actions", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: javascript-actions
GitHub stars: 128
Token cost: ~1.4k tokens
SKILL.md length: 488 words
Files: 1
Skills in repo: 75
Repo updated: Oct 7, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Create, call and drop JavaScript actions — client-side logic called from nanoflows, not microflows.

Works in 2 steps: The model unit… → A source file…
Behaviour must run in the browser
SKILL.md covers When to Use This Skill, Overview, Syntax and Examples, plus 6 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Javascript Actions is an agent skill from mendixlabs/mxcli. Create, call and drop JavaScript actions — client-side logic called from nanoflows, not microflows. Use when behaviour must run in the browser or on the device: DOM, fetch, geolocation, or wrapping a marketplace JS action.

Its SKILL.md is about 1.4k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It works with JavaScript and Java. The repository describes itself as: Mendix cli tool, a headless way to work with Mendix projects. Enables Mendix projects for use with 3rd party agentic coding tools like Claude Code and Copilot. Includes a… The licence is Apache-2.0.

When your agent uses it

Behaviour must run in the browser
On the device: DOM
Wrapping a marketplace JS action

Example prompts

“/javascript-actions”

Workflow steps

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

The model unit (JavaScriptActions$JavaScriptAction).
A source file javascriptsource//actions/.js containing an

What it can do on your machine

Read from SKILL.md and the folder at commit a924d11. 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
No scripts in the folder and no shell commands in SKILL.md (its code samples are sql and javascript).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
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.

Context cost

Javascript Actions loads about 1.4k tokens when it runs. Until then it costs about 60 tokens; SKILL.md has 488 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~60
When it runs · the whole SKILL.md, loaded when a task matches: ~1.4k

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

The full file from mendixlabs/mxcli at commit a924d11, republished under its Apache-2.0 licence (© mendixlabs). 488 words, ~1,449 tokens.

Download SKILL.mdSave it as .claude/skills/javascript-actions/SKILL.md (or your agent's skills folder).

name: javascript-actions
description: Create, call and drop JavaScript actions — client-side logic called from nanoflows, not microflows. Use when behaviour must run in the browser or on the device: DOM, fetch, geolocation, or wrapping a marketplace JS action.

Mendix JavaScript Actions Skill

Guidance for creating, calling, and dropping JavaScript actions in Mendix projects with MDL. JavaScript actions hold custom client-side logic and are called from nanoflows (not microflows — those use Java actions).

When to Use This Skill

Adding client-side behaviour (browser/native APIs, DOM, fetch, geolocation, …)
Logic that must run on the device rather than the server
Calling an existing JavaScript action from a nanoflow
Wrapping a marketplace/native capability exposed as a JS action

For server-side custom code, use Java actions instead (see java-actions).

Overview

A JavaScript action is two things on disk:

The model unit (JavaScriptActions$JavaScriptAction).
A source file javascriptsource/<Module>/actions/<Name>.js containing an exported async function.

CREATE JAVASCRIPT ACTION writes both. The MDL body you provide becomes the function body (between the BEGIN USER CODE / END USER CODE markers), so it normally returns a Promise.

Syntax

sql

CREATE [OR MODIFY] JAVASCRIPT ACTION Module.Name ( parameters )
    RETURNS type
    [EXPOSED AS 'caption' IN 'category']
    [PLATFORM Web | Native | Hybrid | All]   -- default Web
AS $$
    <javascript>
$$;

DROP JAVASCRIPT ACTION Module.Name;

Clause order is fixed: returns, then exposed as, then platform, then as.

AS $$ ... $$ is mandatory. Omitting the body causes no viable alternative at input '...'. Use a stub: AS $$ return Promise.resolve(false); $$.
PLATFORM defaults to Web. Use Native, Hybrid, or All to widen.
OR MODIFY updates an existing action in place (UUID preserved); without it, a duplicate name is an error (use create or modify to overwrite).

Parameter types

Same type system as Java actions:

Primitives: String, Integer, Long, Decimal, Boolean, DateTime
Entity: Module.EntityName · List: List of Module.EntityName
Enumeration: ENUM Module.EnumName
Type parameter (generics): declare EntityType: ENTITY <pEntity>, then use the bare pEntity for instance parameters
Append NOT NULL to mark a parameter required.

Examples

Simple action (Web default):

sql

mdl 1;
CREATE JAVASCRIPT ACTION MyFirstModule.JSA_IsOnline () RETURNS Boolean
AS $$
    return Promise.resolve(navigator.onLine);
$$;

Parameters + return:

sql

mdl 1;
CREATE JAVASCRIPT ACTION MyFirstModule.JSA_Add (
    A: Integer NOT NULL,
    B: Integer NOT NULL
) RETURNS Integer
AS $$
    return Promise.resolve(A + B);
$$;

Exposed toolbox action, native platform:

sql

mdl 1;
CREATE JAVASCRIPT ACTION MyFirstModule.JSA_ShowToast (
    Message: String NOT NULL,
    Duration: Integer
) RETURNS Boolean
EXPOSED AS 'Show Toast' IN 'UI'
PLATFORM Native
AS $$
    console.log(Message);
    return Promise.resolve(true);
$$;

Idempotent update (UUID preserved):

sql

mdl 1;
CREATE OR MODIFY JAVASCRIPT ACTION MyFirstModule.JSA_Add (
    A: Integer NOT NULL,
    B: Integer NOT NULL,
    C: Integer
) RETURNS Integer
AS $$
    return Promise.resolve(A + B + (C || 0));
$$;

Drop (removes the unit and the .js file):

sql

mdl 1;
DROP JAVASCRIPT ACTION MyFirstModule.JSA_Add;

Show full SKILL.md (213 more words)Show less

Calling from a nanoflow

JavaScript actions are invoked with CALL JAVASCRIPT ACTION inside a nanoflow body (arguments use Name = value):

sql

$Sum = call javascript action MyFirstModule.JSA_Add(A = 2, B = 3);

This is the nanoflow counterpart of CALL JAVA ACTION (microflows). Use it in a CREATE NANOFLOW ... BEGIN ... END; body.

The generated .js file

CREATE writes (and OR MODIFY rewrites) javascriptsource/<Module>/actions/<Name>.js:

javascript

// This file was generated by Mendix Studio Pro.
// ...
// BEGIN EXTRA CODE
// END EXTRA CODE

/**
 * @param {number} A
 * @param {number} B
 * @returns {Promise.<number>}
 */
export async function JSA_Add(A, B) {
    // BEGIN USER CODE
    return Promise.resolve(A + B);
    // END USER CODE
}

Only the code between the USER CODE / EXTRA CODE markers is preserved when Studio Pro regenerates the file. The MDL $$ body $$ lands inside USER CODE.

Inspecting

sql

LIST JAVASCRIPT ACTIONS [IN Module];
DESCRIBE JAVASCRIPT ACTION Module.Name;   -- re-executable MDL (signature + body)

DESCRIBE output round-trips: it re-parses as a CREATE JAVASCRIPT ACTION.

Validation Checklist

Body present: AS $$ ... $$; — never omit it
Body returns a Promise (the function is async)
Clause order: returns → exposed as → platform → as
Required parameters marked NOT NULL
Use CALL JAVASCRIPT ACTION from nanoflows, CALL JAVA ACTION from microflows
Validate before applying: mxcli check script.mdl

Common Errors

Symptom	Cause	Fix
`no viable alternative at input '...'`	Missing `AS $$ ... $$` body	Add a body (stub `return Promise.resolve(false);`)
`already exists — use create or modify to overwrite`	Duplicate name without `OR MODIFY`	Add `OR MODIFY`
Action runs nowhere / wrong client	`PLATFORM` too narrow	Set `PLATFORM All` (or the right target)
`mismatched input 'platform'`	Clause out of order	Put `platform` after `exposed as`, before `as`

java-actions — server-side custom code (microflows)
write-nanoflows — nanoflow syntax and restrictions
mxcli syntax javascript-action — quick syntax reference

Files

Just SKILL.md in .claude/skills/mendix/javascript-actions of mendixlabs/mxcli.

Open the folder on GitHubat commit a924d11

Compare with similar skills

Javascript Actions 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.

Javascript Actions compared with similar skills
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Code Audit3stoneBrother/code-audit	893	1 repos	~2.7k	Automated safety check: Pass	None	7 mo ago
CodeQL Security Scantrailofbits/skills	7.4k	—	~4.6k	Automated safety check: Notes	CC-BY-SA-4.0	5 days ago
Fory Version Bumpapache/fory	4.6k	—	~1.1k	Automated safety check: Pass	Apache-2.0	today
Dr Jskilljdubois/dr-jskill	342	—	~4.6k	Automated safety check: Notes	Apache-2.0	8 days ago

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Questions about Javascript Actions

What does Javascript Actions do?

Create, call and drop JavaScript actions — client-side logic called from nanoflows, not microflows. Javascript Actions is an agent skill from mendixlabs/mxcli. Create, call and drop JavaScript actions — client-side logic called from nanoflows, not microflows.

When should I use Javascript Actions?

Javascript Actions fits situations like: behaviour must run in the browser; on the device: DOM; wrapping a marketplace JS action.

How do I install Javascript Actions in Claude Code?

Run `npx skills add mendixlabs/mxcli --skill javascript-actions -a claude-code`. Or copy the skill folder (.claude/skills/mendix/javascript-actions in mendixlabs/mxcli) into .claude/skills/javascript-actions in your project. Claude Code loads it when a task matches its description.

How do I install Javascript Actions in Codex?

Run `npx skills add mendixlabs/mxcli --skill javascript-actions -a codex`. Or copy the skill folder (.claude/skills/mendix/javascript-actions in mendixlabs/mxcli) into .agents/skills/javascript-actions in your project. Codex loads it when a task matches its description.

Can I use Javascript Actions 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 mendixlabs/mxcli --skill javascript-actions -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/javascript-actions, .gemini/skills/javascript-actions, .github/skills/javascript-actions and .opencode/skills/javascript-actions in your project.

What does Javascript Actions need to run?

SKILL.md names no scripts, command-line tools or credentials: Javascript Actions is instructions for the agent only.

Does Javascript Actions 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 Javascript Actions 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 Javascript Actions use?

Javascript Actions is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Javascript Actions use?

About 1.4k tokens (SKILL.md is roughly 5.8k 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 Javascript Actions?

Skills that share tags, products or a category with Javascript Actions: Fory Release (apache/fory, 4.6k stars), Code Audit (3stoneBrother/code-audit, 893 stars), CodeQL Security Scan (trailofbits/skills, 7.4k stars) and Fory Version Bump (apache/fory, 4.6k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Javascript Actions?

mendixlabs (a GitHub organization) maintains it in mendixlabs/mxcli, which has 128 GitHub stars. The repository holds 75 skills in this directory. The repository was last updated on October 7, 2026.

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

Install Javascript Actions

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Mendix JavaScript Actions Skill

When to Use This Skill

Overview

Syntax

Parameter types

Examples

Calling from a nanoflow

The generated .js file

Inspecting

Validation Checklist

Common Errors

Related Documentation

Files

Compare with similar skills

Similar skills

More from mendixlabs/mxcli

Related

Questions about Javascript Actions