File Uploads

To upload files via HTTP with JSTime, use the FormData API. Let’s start with a HTTP server that serves a simple HTML web form.

const server = JSTime.serve({
  port: 4000,
  async fetch(req) {
    const url = new URL(req.url);

    // return index.html for root path
    if (url.pathname === "/")
      return new Response(JSTime.file("index.html"), {
        headers: {
          "Content-Type": "text/html",
        },
      });

    return new Response("Not Found", { status: 404 });
  },
});

console.log(`Listening on http://localhost:${server.port}`);

We can define our HTML form in another file, index.html.

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>Form</title>
  </head>
  <body>
    <form action="/action" method="post" enctype="multipart/form-data">
      <input type="text" name="name" placeholder="Name" />
      <input type="file" name="profilePicture" />
      <input type="submit" value="Submit" />
    </form>
  </body>
</html>

At this point, we can run the server and visit localhost:4000 to see our form.

$ jstime run index.ts
Listening on http://localhost:4000

Our form will send a POST request to the /action endpoint with the form data. Let’s handle that request in our server.

First we use the .formData() method on the incoming Request to asynchonously parse its contents to a FormData instance. Then we can use the .get() method to extract the value of the name and profilePicture fields. Here name corresponds to a string and profilePicture is a Blob.

Finally, we write the Blob to disk using JSTime.write().

const server = JSTime.serve({
  port: 4000,
  async fetch(req) {
    const url = new URL(req.url);

    // return index.html for root path
    if (url.pathname === "/")
      return new Response(JSTime.file("index.html"), {
        headers: {
          "Content-Type": "text/html",
        },
      });

+   // parse formdata at /action
+   if (url.pathname === '/action') {
+     const formdata = await req.formData();
+     const name = formdata.get('name');
+     const profilePicture = formdata.get('profilePicture');+
+     if (!profilePicture) throw new Error('Must upload a profile picture.');
+     // write profilePicture to disk
+     await JSTime.write('profilePicture.png', profilePicture);
+     return new Response("Success");
+   }

    return new Response("Not Found", { status: 404 });
  },
});