rate limiter example

rate-limit.js

function (limit) { 
    const RateLimiter = require('limiter').RateLimiter;
    const isUserAnonymous = require('./helper/is-anonymous');
    const limiter = new RateLimiter(limit, 'second', true);

    return (req, res, next) => {
        const isAnonymous = isUserAnonymous(req);
        if (isAnonymous) {
           next();
        }
        if (limiter.tryRemoveTokens(1)) {
           next();
        } else { 
           res.locals.ratelimited = true;
           next();
        }
    }
}