JavaScript Bundling is the practice of taking two small JavaScript files and merging them together to reduce the number of requests to the server thus, having a shorter loading time.
However, there was a bug found in the process of this technique and it turns out that it took much longer to load the merged files than it did to load the smaller files. In the end, the process saved no time at all.
If that is not enough reason to stay away from this practice, developers have since found out that if you are running your website on HTTP2, then it is pointless to use JavaScript Bundling.