trickle/index.js

Slows incoming stream data to specific intervals

var through = require('through');

module.exports = function TrickleStream(options) {
    var options = options || {}
      , queued = []
      , finishing = false
      , interval = false
      , stream

    options.interval = options.interval || 50;
    options.flush = options.flush || 1;
    options.limit = options.limit || 0;
    options.mru = options.mru || false;

    interval = setInterval(function() {
        var next, i

        for (i = 0; i < options.flush; i += 1) {
            next = queued.splice(0, 1)[0];
            if (!next) break;
            if (!i) stream.resume();
            stream.emit('data', next);
        }
        if (finishing && !queued.length) {
            stream.emit('end');
            clearInterval(interval);
        }
    }, options.interval);

    stream = through(function write(data) {
        this.pause();
        if (!options.limit || queued.length < options.limit) {
            queued.push(data);
        } else
        if (options.mru) {
            queued.shift();
            queued.push(data);
        }
    }, function end() {
        finishing = true;
    });

    return stream;
};