As a consequence, JSON in JavaScript is super easy. Using XML is medium-hard.
In .NET using XML or JSON is easy (not super easy).
In C++ using XML or JSON is medium-hard.
Do not know the state of the art for Go, Rust, Java, ...
As a consequence, JSON is - from a JavaScript developer perspective - the holy grail. From a .NET/Java/C++ developer perspective it is just another format.