FancyMenu JavaScript APIlink

FancyMenu injects a JavaScript bridge into every MCEF-backed feature (for example the Browser element). The bridge lets web content:

run any FancyMenu action directly from JavaScript,
read any FancyMenu placeholder asynchronously.

Two globals expose the API:

window.fancymenu – primary namespace
window.FancyMenu – alias (mirrors the exact shape of fancymenu)

Use the fancymenu-ready event, or feature detection, to ensure the bridge is available before calling it.

1. Namespaces & Structurelink

fancymenu.actions – execute FancyMenu actions from the browser.
fancymenu.placeholders – read FancyMenu placeholder values asynchronously.
FancyMenu mirrors fancymenu, so both expose the same sub-namespaces.

Actions expose two helpers:

fancymenu.actions.execute(actionType, actionValue?)
fancymenu.actions.executeWithCallback(actionType, actionValue?, onSuccess?, onFailure?)

2. Availabilitylink

if (typeof fancymenu !== 'undefined') {
    // safe to use
}

window.addEventListener('fancymenu-ready', () => {
    console.log('FancyMenu API is ready');
});

Content may also be hosted locally: place HTML files in <game-directory>/config/fancymenu/assets/ and load them through URLs of the form file:///config/fancymenu/assets/<name>.html.

3. Executing Actionslink

Use the fancymenu.actions namespace. Each call mirrors the action strings used in FancyMenu scripts.

Quick Callslink

fancymenu.actions.execute('quitgame');                // action without value
fancymenu.actions.execute('opengui', 'title_screen'); // action with value
fancymenu.actions.execute('set_variable', 'hp:20');   // value uses name:value format

With Callbackslink

fancymenu.actions.executeWithCallback(
    'opengui',
    'title_screen',
    result => console.log('Opened title screen'),
    error  => console.error('Open failed:', error)
);

// The value parameter is optional. When omitted, pass the callbacks directly after actionType.
fancymenu.actions.executeWithCallback(
    'quitgame',
    result => console.log('Quit triggered'),
    error  => console.error('Quit failed:', error)
);

Legacy helpers fancymenu.execute(...) and fancymenu.executeWithCallback(...) still delegate to the actions namespace.

Common Action Typeslink

quitgame – immediately quits the game (no value)
back_to_last_screen – returns to the previous GUI (no value)
opengui – opens a FancyMenu or vanilla screen (value: screen identifier)
openlink – launches a browser (value: URL)
sendmessage – posts a chat line (value: message text)
set_variable – assigns a FancyMenu variable (value: name:value)
joinserver – connects to a server (value: address)
disconnect_server_or_world – disconnects and moves to a target screen (value: screen identifier)

Every action that exists in FancyMenu is available through the bridge; see action scripts for the complete catalog.

4. Reading Placeholderslink

FancyMenu’s placeholder system is exposed through fancymenu.placeholders (and FancyMenu.placeholders). Both helper methods return Promise<string>:

fancymenu.placeholders.get(identifier: string): Promise<string>
fancymenu.placeholders.getWithVars(identifier: string, ...vars: string[]): Promise<string>

Supplying Variableslink

Variables are strings in name:value form. The bridge splits on the first colon only, so the value can contain additional colons.
Names and values are trimmed; empty names are rejected.
Provide as many variables as the placeholder requires. Omit optional ones.

Exampleslink

// No variables
fancymenu.placeholders.get('playername')
    .then(name => console.log('Player:', name));

// One variable
fancymenu.placeholders.getWithVars('uptime_duration', 'output_as_millis:false')
    .then(seconds => console.log('Uptime (s):', seconds));

// Multiple variables
fancymenu.placeholders.getWithVars(
    'split_text',
    'input:apple|banana|carrot',
    'regex:\\|',
    'max_parts:-1',
    'split_index:1'
).then(part => console.log('Selected part:', part));

Error Modellink

Rejected promises contain a structured error:

interface PlaceholderError {
    code: 'NOT_FOUND' | 'MISSING_VARIABLE' | 'INVALID_VARIABLE' | 'EVALUATION_ERROR' | 'INTERNAL_ERROR';
    message: string;
    details?: unknown;
}

Example handling:

fancymenu.placeholders.get('unknown')
    .catch(error => console.warn(error.code, error.message));

5. Complete Examplelink

<!DOCTYPE html>
<html>
<head>
    <title>FancyMenu Integration</title>
</head>
<body>
    <h1>Game Controls</h1>
    
    <button onclick="quitGame()">Quit Game</button>
    <button onclick="openTitleScreen()">Title Screen</button>
    <button onclick="disconnectFromServer()">Disconnect</button>
    <button onclick="setVariable()">Set Variable</button>
    <button onclick="loadPlaceholders()">Load Placeholders</button>

    <div id="placeholderOutput" style="margin-top:16px;font-family:monospace"></div>
    
    <script>
        function getActions() {
            if (typeof fancymenu === 'undefined') {
                console.warn('FancyMenu API is not available yet.');
                return null;
            }
            return fancymenu.actions || fancymenu;
        }

        function quitGame() {
            const actions = getActions();
            if (!actions) return;
            actions.execute('quitgame');
        }
        
        function openTitleScreen() {
            const actions = getActions();
            if (!actions) return;
            actions.executeWithCallback(
                'opengui',
                'title_screen',
                () => console.log('Title screen opened!'),
                err => console.error('Error:', err)
            );
        }
        
        function disconnectFromServer() {
            const actions = getActions();
            if (!actions) return;
            actions.execute('disconnect_server_or_world', 'title_screen');
        }
        
        function setVariable() {
            const actions = getActions();
            if (!actions) return;
            var varName = prompt('Variable name:');
            var varValue = prompt('Variable value:');
            if (varName && varValue) {
                actions.execute('set_variable', varName + ':' + varValue);
            }
        }

        function loadPlaceholders() {
            if (typeof fancymenu === 'undefined' || !fancymenu.placeholders) {
                console.warn('FancyMenu placeholder API is not available yet.');
                return;
            }

            Promise.all([
                fancymenu.placeholders.get('playername'),
                fancymenu.placeholders.getWithVars('uptime_duration', 'output_as_millis:false'),
                fancymenu.placeholders.getWithVars(
                    'split_text',
                    'input:apple|banana|carrot',
                    'regex:\\|',
                    'max_parts:-1',
                    'split_index:1'
                )
            ]).then(([playerName, uptimeSeconds, secondFruit]) => {
                document.getElementById('placeholderOutput').textContent =
                    'Player: ' + playerName + '\n' +
                    'Uptime (seconds): ' + uptimeSeconds + '\n' +
                    'Second fruit: ' + secondFruit;
            }).catch(error => {
                console.error('Placeholder request failed:', error);
            });
        }
    </script>
</body>
</html>

6. Best Practices & Noteslink

Detect the bridge before using it, or listen for fancymenu-ready.
Handle errors (callbacks for actions, .catch for placeholders) to present useful feedback.
Validate input before passing it to actions or placeholder variables.
Throttle requests; avoid spamming the bridge with rapid-fire calls (especially placeholder refresh loops).
Security: Browser content can invoke any registered FancyMenu action, including file, network, command, clipboard, resource-pack, link, and quit actions. Load only trusted pages, and validate all data received from web content.

7. Troubleshootinglink

Confirm the page is loaded in a FancyMenu-controlled MCEF browser.
Check the browser console for JavaScript errors.
Verify the placeholder identifier or action type is correct and that required values are supplied.
Review the Minecraft log (latest.log) for FancyMenu error messages if execution fails unexpectedly.