I developed Yet Another JSON Templating Language, whose main virtue was that it was extremely simple to use and implement, and it could be easily implemented in JavaScript or any other languages supporting JSON.

We had joy, we had fun, we had seasons in the sun, but as I added more and more features and syntax to cover specific requirements and uncommon edge cases, I realized I was on an inevitable death-march towards my cute little program becoming sufficiently complicated to trigger Greenspun's tenth rule.

https://en.wikipedia.org/wiki/Greenspun%27s_tenth_rule

There is no need for Yet Another JSON Templating Language, because JavaScript is the ultimate JSON templating language. Why, it even supports comments and trailing commas!

Just use the real thing to generate JSON, instead of trying to build yet another ad-hoc, informally-specified, bug-ridden, slow implementation of half of JavaScript.