What is the method for my Discord Bot to mention a user I've referred to?

I recently began developing a Discord bot and encountered an issue with user mentions. My goal is for the bot to acknowledge and compliment users whenever I mention them in any channel. For example:

Dahkris: lul howcool @Myfriend
Bot: @Myfriend is 80% cool!

(The randomness is already functioning.)
As a beginner in JavaScript, I’m uncertain about how to access user mentions and whether to utilize @member or ‘member.displayName’, among other options (I’ve experimented with various approaches).
I’ve researched similar examples, but most of the time, the bot only mentions the message’s author. Here’s my current code:

bot.on('message', message => {
    if (message.startsWith('lul howcool')) {
      if (message.content.includes('@member')) {
        message.channel.send('@member is ' + (Math.floor(Math.random() * 100) + 1) + '% cool!');
      }
    }
});

This implementation appears error-free, but it fails to execute as the message doesn’t seem to include ‘@member’ in the way I expect.