In fact, malformed XML is more frequent than malformed JSON, and it's not hard to see why. JSON types match the basic object model of many dynamic languages; n

In fact, malformed XML is more frequent than malformed JSON, and it's not hard to see why. JSON types match the basic object model of many dynamic languages; not just JavaScript, but also Python and to a lesser extent Lua and PHP. So when people want to generate JSON, they usually do it the 'proper' way: by constructing a native structure consisting of built-in dictionaries and lists in their language of choice and then serialising it to a string. This always generates valid JSON syntax; the worst risk is that an empty dictionary could be mis-serialised as an empty array or vice versa, in languages that don't distinguish the two. XML has no such easy support; when you generate XML, the least-effort solution is to use sprintf (or an equivalent), which creates the hazard of the programmer forgetting to escape syntax-significant characters (and let's not forget binary/text confusion in some languages). JavaScript had to evolve E4X and JSX to solve the interpolation problem with XML. It didn't have to create any new syntax to support JSON; it is purely a library feature. Of course, some programming languages favour neither, like C or Java.