function concat (type, dataArray) {
    var i, index = 0, res = null, totalLength = 0;
    for(i = 0; i < dataArray.length; i++) {
        totalLength += dataArray[i].length;
    }
    switch(type) {
        case "string":
            return dataArray.join("");
          case "array":
            return Array.prototype.concat.apply([], dataArray);
        case "uint8array":
            res = new Uint8Array(totalLength);
            for(i = 0; i < dataArray.length; i++) {
                res.set(dataArray[i], index);
                index += dataArray[i].length;
            }
            return res;
        case "nodebuffer":
            return Buffer.concat(dataArray);
        default:
            throw new Error("concat : unsupported type '"  + type + "'");
    }
}
Concatenate an array of data of the given type.
@param {String} type the type of the data in the given array.
@param {Array} dataArray the array containing the data chunks to concatenate
@return {String|Uint8Array|Buffer} the concatenated data
@throws Error if the asked type is unsupported