On this page

Creating a URL Type

Let’s create a simple type for encoding URLs. As an example, we’ll use URLs with the http or https protocol.

type TURL = `https://${string}` | `http://${string}`;
const urlRegEx = /^https?:\/\//;

export const url = customType<TURL>({
  encode(value, buffer) {
    // Encode protocol: http as 1, https as 2
    buffer.writeUint8(value.startsWith("https") ? 2 : 1);
    // Encode the rest of the URL
    buffer.writeString(value.slice(value.indexOf("://") + 3));
  },
  decode(buffer) {
    const protocol = buffer.readUint8();
    const url = buffer.readString();
    return `${protocol === 2 ? "https" : "http"}://${url}`;
  },
  guard(data): data is TURL {
    if (typeof data !== "string") return false;
    if (!urlRegEx.test(data)) return false;
    return true;
  },
  name: "url",
});

Now we can use this type in our data schema:

import { Serializer, t } from "encodexx";
import { url } from "./url.ts";

const serializer = new Serializer([url]);