Simple Mastodon bot in 100 lines.

mastodon.js

const fetch = require('node-fetch');

const createHiddenField = (obj, fieldName, value) => {
    Object.defineProperty(obj, fieldName, {
        enumerable: false,
        writable: true,
        value: value,
    });
};

class MastodonClient {
    constructor(client_key, client_secret) {
        if (!client_key) throw new Error('client key is requuired');
        if (!client_secret) throw new Error('client secret is required');

        this.baseUrl = 'https://techhub.social';
        this.userAgent = 'nekzbot';
        this.loginData = null;

        this.client_key = client_key;
        createHiddenField(this, 'client_secret', client_secret);
    }
    authorizationUrl() {
        return `${this.baseUrl}/oauth/authorize?response_type=code&client_id=${this.client_key}&redirect_uri=urn:ietf:wg:oauth:2.0:oob&scope=write`;
    }
    async login(code) {
        const data = {
            grant_type: code ? 'authorization_code' : 'client_credentials',
            client_id: this.client_key,
            client_secret: this.client_secret,
            redirect_uri: 'urn:ietf:wg:oauth:2.0:oob',
            scope: 'write',
            code,
        };
        const res = await fetch(`${this.baseUrl}/oauth/token`, {
            method: 'POST',
            headers: {
                'User-Agent': this.userAgent,
                'Content-Type': 'application/x-www-form-urlencoded',
            },
            body: Object.entries(data)
                .filter((x) => x)
                .map(([key, value]) => `${encodeURIComponent(key)}=${encodeURIComponent(value)}`)
                .join('&'),
        });

        this.loginData = await res.json();
        return this;
    }
    async publishStatus(status) {
        const token = this.loginData?.access_token;
        if (!token) throw Error('not logged in');

        const data = {
            status,
        };

        const res = await fetch(`${this.baseUrl}/api/v1/statuses`, {
            method: 'POST',
            headers: {
                'User-Agent': this.userAgent,
                'Content-Type': 'application/x-www-form-urlencoded',
                'Authorization': 'Bearer ' + token,
            },
            body: Object.entries(data)
                .map(([key, value]) => `${encodeURIComponent(key)}=${encodeURIComponent(value)}`)
                .join('&'),
        });

        const json = await res.json();

        return this;
    }
}

async function main() {
    const client = new MastodonClient(
        'CLIENT KEY',
        'CLIENT SECRET',
    );

    const stdin = process.openStdin();

    process.stdout.write(`Authorize Mastodon Client: ${client.authorizationUrl()}\n\nEnter Authorization Code: `);

    stdin.addListener('data', async (text) => {
        const code = text.toString().trim();
        console.log('[mastodon] Logging in...');

        stdin.pause();

        await client.login(code);
        console.log('[mastodon] Logged in');

        await client.publishStatus(':^)');
    });
}

main();