hubot

Interacting with Your Hubot

To create instructions for your Hubot, you need to add a JavaScript file to the scripts folder. You can add multiple scripts files to that folder and all will execute when the Hubot is run. Let's look at a few commands that will help us build our Hubot scripts.

Listening

.hear

The .hear command listens for a specific phrase anywhere in the Slack room. You don't have to mention your Hubot in order to get a response.

In the example below, when the bot hears "Hello!", it will respond, "Hi there!":

bot.hear(/Hello!/, function(res) {
  return res.send("Hi there!");
});

tim: Hello!
hubot: Hi there!

.respond

.respond is similar to .hear, except it will only be triggered when someone specifically mentions the Hubot using @, or sends a direct message.

bot.respond(/What's your favorite food?/, function(res) {
  return res.send("I'm a robot--I don't eat food!");
});

tim: @hubot What's your favorite food?
hubot: I'm a robot--I don't eat food!
jon: What's your favorite food?
... [no response because Jon didn't tag Hubot in his message]

Speaking Responding to User Input

.send and .reply

The "send" method allows your Hubot to send a message to the channel, and the "reply" method allows it to respond directly to a user with an @ reply. In order to understand the difference, we’ll need to accept some user input, so let's take a look at the example below.

The Wildcard Selector

Would you like to accept user input in your script? Take a look at the example below:

bot.respond(/Hi Hubot! My name is (.*)/i, function(msg) {
  var name;
  name = msg.match[1];
  if (name == "Hubot"){
    return msg.send("You're not Hubot--I'm Hubot!");
  } else {
    return msg.reply("Nice to meet you, " + name + "!");
  }

});

tim: @hubot Hi Hubot! My name is Tim
hubot: @tim Nice to meet you, Tim!  
tim: @hubot Hi Hubot! My name is Hubot
hubot: You're not Hubot--I'm Hubot!

Did you notice the difference between .send and .reply?

Now, let's dig into how the user input works. As you can see, we're using .respond to set the bot up to listen for its @ handle. In this case, it's listening for the phrase @hubot Hi Hubot! My name is _____. The (.*) syntax is a wildcard value that effectively represents the "blank" in that sentence. When the bot is triggered with the phrase, @hubot Hi Hubot! My name is (.*), it stores the contents of (.*) in an array called match, which lives inside an object called msg. When we want to retrieve that value, we use fav = msg.match[0] to grab the first value in that array, which, in this case, is "Tim".

**Wait, What Does the `[1]` Mean?** (click the arrow for the answer)

`msg.match[1]` will grab the value corresponding to the second group `(.*)` in the expression. Just like most collections in JavaScript, this is a zero-based index. However, the first group is the entire expression. So in the example above, `msg.match[0]` will return the entire expression: `Hi Hubot! My name is Tim`. If you use multiple `(.*)`s within one RegEx statement, you can assign each of the values to different variables, such as: `var foo = msg.match[1]`, `var bar = msg.match[2]`.

Here's an example that uses two wildcards:

bot.respond(/add (.*) and (.*)/i, function(msg) {
  var a;
  var b;
  a = parseInt(msg.match[1]);
  b = parseInt(msg.match[2]);
  c = a + b

  return msg.reply(a + " plus " + b + " = " + c);
});

tim: @hubot add 3 and 4
hubot: 3 plus 4 = 7

Here's another example that uses a switch statement to handle different cases:

bot.respond(/what is your favorite (.*)/, function(msg) {
  var fav;
  fav = msg.match[1];
  console.log(fav);
  switch (fav) {
    case "food":
      return msg.reply("I'm a robot--I don't eat food!");
      break;
    case "band":
      return msg.reply("It's gotta be Daft Punk!");
      break;
    case "programming language":
      return msg.reply("Javascript, of course!");
      break;
    default:
      return msg.reply("I don't have a favorite " + fav + ". What's yours?");
  }
});

tim: @hubot what is your favorite food?
hubot: @tim I'm a robot--I don't eat food!
tim @hubot what is your favorite color?
hubot: @tim I don't have a favorite color. What's yours?

Getting Fancy

Regular Expressions You might have noticed that we haven't used quotes around the phrases Hubot is listening for; instead, we’re using / (e.g. /What's your favorite food/). Why do we do this?

Most programming languages allow you to search for text within text using something called Regular Expressions. Regular expressions, or "RegEx," enable you to listen for very specific patterns of text within a document, or, in this case, a chat room.

For example, if you want to find the word "what" using a RegEx, you can use the following code: \bwhat\b. Here, "b" represents the boundaries of the word (i.e., its beginning and end) and the "what" represents the word we are searching for.

This is an advanced example, though. For most of your bots, you can simply enclose phrases between / marks. If you would like to learn more about RegEx, check out the resources below:

• RegexOne walks you through basic to advanced RegEx syntax. Check it out!
• RegExr lets you test out your RegEx without the need to constantly start and stop your bot.

To wrap things up, here's one final example of an advanced Hubot that uses a RegEx, and that can respond to a number of different inputs:

module.exports = function(robot) {
    robot.respond(/is it a (weekend|holiday)\s?\?/i, function(msg){
        var today = new Date();

        msg.reply(today.getDay() === 0 || today.getDay() === 6 ? "YES" : "NO");
    });

    robot.hear(/i did it/i, function(msg){
        msg.send("Congratulations! Good job!");
    });

    robot.respond(/are you there?/i, function(msg){
        msg.reply('Yes, usually here, and listening.');
    });

    robot.respond(/convert \$(.*) to btc/i, function(res){
        var usd = res.match[1];
        res.reply('That is about ' + usd * 0.0024 + ' in BTC');
    });

}