#+TITLE: Finding Non-timeline Tweet In Timeline

We want all the top-level element representing each tweet. Fortunately Twitter provides a convenient class we can select against, ~js-stream-item~. We want to be able to filter that array using ~Array#filter~, but ~document.querySelectorAll~ returns a ~NodeList~, so we convert to an array first.

#+BEGIN_SRC js :exports code :tangle yes
let getAllTweets = () => Array.from(document.querySelectorAll('.js-stream-item'))
#+END_SRC

Given all tweets, we want a filter that keeps just the tweets that don't belong in the timeline so we can do something with those. One way to identify these tweets is by the icons twitter includes in non-chronological tweets to give you the user context of why those tweets are showing up in the timeline. The ~nonchrono~ function looks at the children of the tweet element and if any of the children matches the contextual icon for one of the non-chronological tweets we're looking for – promoted, other user likes, or "your friends follow this person" – we return ~true~ to keep that tweet.

#+BEGIN_SRC js :exports code :tangle yes
let nonchrono = e => {
  for (typ of ['follower', 'promoted', 'heartBadge']) {
    if (e.querySelector(`.tweet-context .Icon--${typ}`)) {
      return true;
    }
  }
  return false;
}
#+END_SRC

We also want a function that will do something with the non-chronological tweets we've found. In our case we just want to highlight them with a red border.

#+BEGIN_SRC js :exports code :tangle yes
let decorate = e => e.style.border = "10px solid red"
#+END_SRC

Putting it together, we get all the tweets, filter down to just the non-chronological tweets, then decorate them.

#+BEGIN_SRC js :exports code :tangle yes
let process => () => getAllTweets().filter(nonchrono).forEach(decorate)
#+END_SRC

New tweets are loaded once the user scrolls near the bottom of the page, so we need to do something to make sure those new tweets get processed. We could probably get sophisticated about this, but for this quick hack we'll continually run ~process~ on a 1000ms timer.

#+BEGIN_SRC js :exports code :tangle yes
let timer = window.setInterval(process, 1000)
#+END_SRC