How can I make discord.js bot detect an attachment

Question

I'm trying to make my Discord bot invert an attachment with REST API but I don't know how to change "${message.author.avatarURL}" so it can detect the message attachment instead of the user's avatar. What should I do?

else if (message.content.toLowerCase() === 'invert'){
    let link = `https://some-random-api.ml/canvas/invert/?avatar=${message.author.avatarURL({ format: 'png'})}`
    let attachment = new MessageAttachment(link, 'invert.png');
    message.channel.send(attachment);
}

Answer 1

Message#attachments

message.attachments is a message object property that returns an array of all attachment objects inside of a message. Knowing that we can now get the first message attachment and get its URL using the following code:

else if (message.content.toLowerCase() === 'invert'){
  const attachmentURL = message.attachments.first();
  if (!attachmentURL) return message.reply('Please provide an image!');
  let link = `https://some-random-api.ml/canvas/invert/?avatar=${attachmentURL.url}`
  let attachment = new MessageAttachment(link, 'invert.png');
  message.channel.send(attachment);
}