I've never done it with JS. It's not really a problem in C, though. If there's a lot of data, you're no better off with text; if there's not much, reading binary data isn't too bad. You've usually got other problems on top of decoding the actual data - like, why is this data coming in the first place? Why isn't the code accepting it properly? Why isn't the other end listening? The data encoding is just the tip of the iceberg.
Either way, the advantages of binary often outweigh the difficulty of having a human read the data. As the saying goes, code is executed far more often than it's read.
(Most binary formats have some fairly obvious possible text representations, at least for key fields (they're just encoding ints, floats, strings, bitfields, etc.). When you're having difficulty, or you're simply curious, you can print them out. If the format is any good, malformed messages are easy to check for in code - this code is not harder to debug than any other. If anything it's actually easier than with some kind of text format.)
I regularly MITM a connection between a mobile app and a HTTP server, when something isn't going quite right. A look at the JSON they exchange exposes the problem in under a minute more often than not. If I want to test something out quickly, I simply modify the incoming / outgoing JSON by hand. It's rare to get the syntax wrong and involves no context switches. I can then go back to the code, find the relevant section and make the changes I need to make. I find this a very convenient way of debugging and I don't think it would be as nice to do this with a binary format.
True. Fortunately, we can be reasonably sure there will be multiple good tools to debug something talking over HTTP 2.0. With something like Transit, I'm not so sure.
Either way, the advantages of binary often outweigh the difficulty of having a human read the data. As the saying goes, code is executed far more often than it's read.
(Most binary formats have some fairly obvious possible text representations, at least for key fields (they're just encoding ints, floats, strings, bitfields, etc.). When you're having difficulty, or you're simply curious, you can print them out. If the format is any good, malformed messages are easy to check for in code - this code is not harder to debug than any other. If anything it's actually easier than with some kind of text format.)