Calling Javascript from Scala.js

Question

I use a Page.scala to start the Client-side of a Scala.js application. Thus Page.scala replaces index.html. The Scalatags raw function allows actual JavaScript to be included. In the Scalatags documentation the example is alert('Hello!'). I actually have a little bit of JavaScript that works out what the browser is, but saying "Hello!" is good for a start. The JavaScript itself is the get_browser_info() function here.

So my question is, can I call this little bit of JavaScript from within Scala code? And is that a sensible way of going about discovering the browser the user is using? I will want to send this information back to the Server.

Of course I could translate the function into Scala, but the JavaScript that checks the browser isn't that easy for me to read - I've never been a JavaScript programmer.

A translation would be great, even if it it would only nearly be answering the core question.

EDIT @sjrd gave the answer from the startup Scala code. To give the complete picture this is what Page.scala looks like:

object Page{
  val boot =
    "simple.MyScalaClient().main(document.getElementById('contents'))"
  val browserVersionFn = "<script>function get_browser_info(){var ua=navigator.userAgent ... version: M[1]};}</script>"
  val skeleton =
    html(
      head(
        meta(charset:="utf-8"),
        script(src:= "/myappname/myappname-fastopt.js"),
        link(
          rel:="stylesheet",
          href:="http://yui.yahooapis.com/pure/0.5.0/pure-min.css"
        )
      ),
      body(
        style := "margin:30",
        onload := boot,
        div(id:="contents"),
        raw(browserVersionFn)
      )
    )
}

score 5 · Accepted Answer · answered Jul 22 '15 at 04:11

Once the script is executed, the get_browser_info is just like any JavaScript library, from Scala.js' point of view. You can therefore call it in a dynamically-typed way like this:

val browser = js.Dynamic.global.get_browser_info()
val name = browser.name.asInstanceOf[String]
val version = browser.version.asInstanceOf[String]

Or you can define a static type facade of you prefer.

Calling Javascript from Scala.js

1 Answers1