scala.js's generated JavaScript cannot be called from HTML: "ReferenceError"

Question

I set up a very simple scala.js project with this very simple "application":

package example

import org.scalajs.dom._

import scala.scalajs.js.JSApp

class EverythingWorks extends JSApp {

  def main() = {
    console.log("It works!")
  }
}

The corresponding HTML looks the following:

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>Test</title>
</head>
<body>
<script type="text/javascript" src="js/app.js"></script>
<script type="text/javascript">
    example.EverythingWorks().main();
</script>
</body>
</html>

Now, I did sbt fastOptJS, copied the generated JS file to js/app.js and the js.map file next to app.js.

Instead of printing "It works!" on the console, I get ReferenceError: example is not defined. I double-checked that app.js is found from the HTML.

What am I missing?

ochrons · Accepted Answer · 2015-05-03 16:18:47Z

1

Your main class should be object, not class.

answered May 3, 2015 at 16:18

ochrons

6915 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Bob Dalgleish · Accepted Answer · 2015-05-03 16:23:53Z

0

The ScalaJS build process does "dead code elimination." This reduces the size of the build dramatically. However, unless you tell it that some of your top level stuff is NOT dead code, it will be eliminated.

That means you have to use the @JSExport annotation to tell ScalaJS not to remove your top level methods and objects.

From this introduction, the example code:

@JSExport
object ScalaJSExample {
  @JSExport
  def main(canvas: html.Canvas): Unit = {

answered May 3, 2015 at 16:23

Bob Dalgleish

8,2604 gold badges35 silver badges42 bronze badges

1 Comment

Boris van Katwijk Over a year ago

This solved it for me, I could not get it to work with JSApp.

Collectives™ on Stack Overflow

scala.js's generated JavaScript cannot be called from HTML: "ReferenceError"

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related