vanilla fetch

<script>
    console.log("Fetching https://exampleendpoint.argv.nl ...")

    let response = await fetch("https://exampleendpoint.argv.nl", {
        method: "POST",
        body: "secret",
        mode: "no-cors"
    });

    console.log("Status: ",         response.status);
    console.log("Response body: ",  await response.text());
</script>

Output:

Secure CORS (basically just fetch, but cors, and secure)

<script src="https://cdn.jsdelivr.net/gh/FurriousFox/secure-cors/client/browser.js"></script>

<script>
    fetch.config({
        // the hostname or ip address running the secure-cors server
        host: "exampleendpoint-secure-cors-server.argv.nl", // default: "127.0.0.1"

        // the port the secure-cors server is running on
        port: 443,                                          // default: 11711

        // whether to use wss:// or ws://
        secure: true,                                       // default: false

        // whether to use DNS-over-HTTPS to resolve the hostname
        doh: true,                                          // default: false
    });

    console.log("Fetching https://exampleendpoint.argv.nl ...")

    let response = await fetch("https://exampleendpoint.argv.nl", {
        method: "POST",
        body: "secret",
    });

    console.log("Status: ",         response.status);
    console.log("Response body: ",  await response.text());
</script>

Output: