The Webstream's module supports mutlipart/x-mixed-replace content with the following configuration

            options = "multipart";

`streamer -U -n data.json -R srv/www/webstream`

webstreammultipart.js offers the fetchmultipart(url) to receive and parse the stream

            function read(reader) {
              reader.read()
              .then(function({done, value}) {
                if (done)
                {
                  throw Error("Connection closed");
                }
                if (value.headers.get("Content-Type") != "text/json")
                {
                  throw Error("Message Not a JSON");
                }
                return value.json();
              })
              .then(function(json) {
                let field = document.querySelector("#value");
                field.setAttribute("value", json.data);
                read(reader);
              })
            }
            fetchmultipart("data.json")
            .then(function(rs) {
              let reader = rs.getReader();
              read(reader);
            })
            .catch(function(error) {
            console.log(error.message);
            });