You're right. so it was the reason I asked you about 'vegalite=require(@observablehq/vega-lite') sentence. If we use this , then it uses vega-lite API 4 version. If we use 'import { vl } from "@vega/vega-lite-api-v5', we can use API 5 but I think we need to change all of our codes into different style. Like this: https://observablehq.com/@vega/vega-lite-api-v5