How do I do this with the user agent?

If the user-agent includes the word "myapp", then alert('hi');

BTW, I am using JQuery.

From stackoverflow

• if (navigator.userAgent.indexOf("myapp") !== -1) {
    alert("hi");
  }
  

  I recommend you don't do user-agent sniffing.

  Justin Johnson : +1 For the recommendation against sniffing. For the rest of the class: Instead of user-agent sniffing, *feature detection* should be used to determine the type of browser that you are dealing with.