Example of an async OpenRCT2 plugin

async-plugin.ts

/// <reference path="C:/Users/Ted/Documents/GitHub/openrct2/distribution/openrct2.d.ts" />

function nextTick() {
    return new Promise<void>((resolve, reject) => {
        try {
            const subscription = context.subscribe('interval.tick', () => {
                try {
                    subscription.dispose();
                    resolve();
                } catch (e) {
                    reject(e);
                }
            });
        } catch (e) {
            reject(e);
        }
    });
}

async function getAverageGrassLength() {
    let steps = 0;
    let grassLength = 0;
    let grassCount = 0;
    const size = map.size;
    for (let y = 0; y < size.y; y++) {
        for (let x = 0; x < size.x; x++) {
            const tile = map.getTile(x, y);
            const numElements = tile.numElements;
            for (let i = 0; i < numElements; i++) {
                const el = tile.getElement(i);
                switch (el.type) {
                    case 'surface':
                        const surfaceEl = el as SurfaceElement;
                        const obj = context.getObject('terrain_surface', surfaceEl.surfaceStyle);
                        if (obj && obj.identifier === 'rct2.surface.grass') {
                            grassLength += surfaceEl.grassLength;
                            grassCount++;
                        }
                        break;
                }
            }

            steps++;
            if (steps >= 1000) {
                steps = 0;
                await nextTick();
            }
        }
    }

    if (grassCount == 0) return 0;
    return Math.round(grassLength / grassCount);
}

const main = () => {
    if (typeof ui === 'undefined') {
        console.log("Plugin not available on headless mode.");
        return;
    }

    ui.registerMenuItem('async test', async () => {
        const grassLen = await getAverageGrassLength();
        park.postMessage('Average grass length: ' + grassLen);
    });
};

registerPlugin({
    name: 'Async Test',
    version: '1.0',
    authors: ['OpenRCT2'],
    type: 'remote',
    licence: 'MIT',
    main: main
});