anchor.diff:  ============
   
   https://github.com/fomkin/korolev/blob/v0.13.0/examples/web-component/src/main/scala/WebComponentExample.scala[See full example]
  +
  +=== Call JavaScript from server
  +
  +Korolev allows executing arbitrary JavaScript code on the client. Use `access.evalJs` to run JavaScript's `eval` method on the client and retrieve the result. The result is a JSON string, so you possibly need to add your favorite https://duckduckgo.com/?q=scala+json+libraries&t=hp&ia=web[JSON library] to project dependencies.
  +
  +[source,scala]
  +-------------------------------------------------------------------------------
  +'button(
  +  "Push me",
  +  event('click)(_.evalJs("1 + 1").map(println)) // 2
  +)
  +-------------------------------------------------------------------------------
  +
  +Also it works for `Promise`.
  +
  +[source,scala]
  +-------------------------------------------------------------------------------
  +'button(
  +  "Push me",
  +  event('click) { access =>
  +    access
  +      .evalJs(
  +        """crypto
  +          |  .subtle
  +          |  .digest('sha-256', Uint8Array.from([1, 2, 3]))
  +          |  .then((res) => {
  +          |    return Array.from(new Uint8Array(res))
  +          |      .map(x => x.toString(16).padStart(2, '0'))
  +          |      .join('')
  +          |  })
  +        """.stripMargin
  +      )
  +      .map(println) // "039058c6f2c0cb492c533b0a4d14ef77cc0f78abccced5287d84a1a2011cfb81"
  +  }
  +)
  +-------------------------------------------------------------------------------
  +
  +== Productivity
   
   === Developer mode and "hot reload"
   
  
positive.code: 
  === Quick start
  
  You need SBT 0.13.15 and JDK 8+ installed. Once installed, run g8 template.
  
  [source,bash]
  -----------------------------------
  
negative.code: 
  https://github.com/fomkin/korolev/blob/v0.13.0/examples/context-scope/src/main/scala/ContextScopeExample.scala[See full example]
  
  == JavaScript interoperability
  
  === WebComponents
  
  If you need to extend your application with something that you can't implement with Korolev, you may use https://github.com/w3c/webcomponents[Web Components]. In simple terms, it is a standard technology that allows you to create custom HTML tags.
  
  [NOTE]
  ============
  