How do I tell if a user is using Brave as their browser?

There is a way to check if the user is using brave without any api calls. I created the below function that returns false or True if its Brave

function isBrave() {
  if (window.navigator.brave != undefined) {
    if (window.navigator.brave.isBrave.name == "isBrave") {
      return true;
    } else {
      return false;
    }
  } else {
    return false;
  }
}

document.getElementById("ans").innerHTML = isBrave();

Is this Brave? <span id="ans"></span>

As of April 2020, you can use this detection method to get a boolean answer to whether the user is using Brave or not:

(navigator.brave && await navigator.brave.isBrave() || false)

The "Brave" in the user agent was removed in the 0.9 version.

From the changelog:

Removed Brave from the User Agent HTTP header to reduce fingerprinting.