Sample Program To Put Block In Minecraft From Node.js

minecraft_set_block.js

const WebSocket = require('ws');
const app = require('express')();
const server = require('http').Server(app);
const uuid = require('uuid/v4');

// Creates a JSON string for "setblock" command request
function setBlockCommand(x, y, z, blockType) {
    return JSON.stringify({
        "body": {
            "origin": {
                "type": "player"
            },
            "commandLine": util.format("setblock %s %s %s %s", x, y, z, blockType),
            "version": 1
        },
        "header": {
            "requestId": uuid(),
            "messagePurpose": "commandRequest",
            "version": 1,
            "messageType": "commandRequest"
        }
    });
}

// Creates a JSON string for subscribing "say" events
function subscribePlayerChatEventCommand() {
    return JSON.stringify({
        "body": {
            "eventName": "PlayerMessage"
        },
        "header": {
            "requestId": uuid(), // UUID
            "messagePurpose": "subscribe",
            "version": 1,
            "messageType": "commandRequest"
        }
    });
}

const wss = new WebSocket.Server({server});

wss.on('connection', socket => {
    console.log('user connected');

    socket.send(subscribePlayerChatEventCommand());

    // Event called when any subscribed event is fired
    socket.on('message', packet => {
        console.log('Message Event');
        console.log(packet);
        const res = JSON.parse(packet);

        if (res.header.messagePurpose === 'event' && res.body.properties.Sender !== 'External') {
            if (res.body.eventName === 'PlayerMessage' && res.body.properties.Message.startsWith('build')) {
                console.log('start build');

                socket.send(setBlockCommand('~0', '~0', '~0', 'stonebrick'));
            }
        }
    });

});

server.listen(3000, () => {
    console.log('listening on *:3000');
});