change chunk sizes in a stream

transform.js

var through = require('through2');

function changeChunkSizes() {
    var buff = '';
    var data;
    var keepIdx;
    
    return through(function (chunk, enc, cb) {
        buff += chunk.toString();
        data = keepIdx = undefined;
        
        if (buff.length > 30) {
            // TODO make sure this index does not fall on a \r\n
            keepIdx = parseInt(buff.length / 2, 10);
            data = buff.slice(0, keepIdx);
            buff = buff.slice(keepIdx);

            return cb(null, data);
        }
        
        cb();
    }, function () {
        this.push(buff);
    });
}