Playing around with browser cookies in Scala.js

#scala #webdev #javascript #showdev

Photo by Laura James from Pexels

I spent this weekend playing around with Scala.js and learning how to manipulate browser cookies with it.

Check out the live demo at cookies.awwsmm.com.

The source is available at github.com/awwsmm/CookiesScalaJS.

There are a few cool Scala flairs here, particularly this bit which pattern matches on a regular expression

  def clearAllCookies(): Unit = {
    val Cookie = "([^=]+)=.+".r
    document.cookie.split("; ").foreach {
      case Cookie(key) => clearCookie(key)
      case other => err.println(s"Couldn't parse '$other' as a key=value cookie pair")
    }
  }

In order to ensure that users don't include the ; or = characters in their cookie keys and values (which confuses the parser), I've also added these two little safeguards, as well

    // prevent the user from typing ';' or '=' into the input
    input.addEventListener("keypress", (e: dom.KeyboardEvent) => {
      if (e.key == ";" || e.key == "=") {
        e.preventDefault()
      }
    })

    // prevent the user from pasting ';' or '=' into the input
    input.addEventListener("paste", (e: dom.ClipboardEvent) => {
      val text = e.clipboardData.getData("text")
      if (text.contains(";") || text.contains("=")) {
        e.preventDefault()
      }
    })