[Silphendio]

You mean searching for keys?

  $..book[?@.price<10].title

Yeah, I don't think javascript has that function in the standard library. Writing one is not super complicated, but having to put that into every file (or importing it) is not ideal.

  find_key = (data, key) => {
    if(data instanceof Array){
     return data.map(x=>find_key(x, key)).flat()
    }
    if(data instanceof Object){
     let res = Object.keys(data).map(x=>find_key(data[x], key))
     if(data.hasOwnProperty(key)){
      res.push(data[key])
     }
     return res.flat()
    }
     return []
   }

  find_key(data, "book").filter(x=>x.price < 10).map(x=>x.title)