Say you are sending the data from the back-end to the front-end and you have a time field. With Rust, you are almost 100% certain that you are serializing/deserializing the same type. So if your code compiles, it'll probably work. With JavaScript, there is a good chance that the date String gets misinterpreted somehow and your application misbehaves.
The other advantage: with JavaScript/TypeScript, I find myself frequently getting the output and testing my functions in JavaScript to make sure stuff works. I don't do that when doing Rust -> Rust. If it's a DateTime chrono, the behaviour will be the same.
Also TypeScript is more like type documentation that strong typing enforcement. So it does help but only a little.
The other advantage: with JavaScript/TypeScript, I find myself frequently getting the output and testing my functions in JavaScript to make sure stuff works. I don't do that when doing Rust -> Rust. If it's a DateTime chrono, the behaviour will be the same.
Also TypeScript is more like type documentation that strong typing enforcement. So it does help but only a little.