html-transformer HTML transformer Example import Transformer from "html-transformer"; let env = {};/** set env */ const transformer = new Transformer();transformer.onText(/{{[^}]+}}/, (_, matched) => { return env[matched[1]];}).onTag("*", "placeholder", /{{[^}]+}}/, (_, matched) => { return env[matched[1]];}).onBeforeClosingTag("body", () => { return "<script src=\"inject_some_js.js\"></script>";}).pipe(htmlOutput);htmlInput.pipe(transformer);