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View stateful_spa.scala
// Overview of how this works:
// 1. Initialisation data is used to create an instance of LoadedRoot.
// 2. LoadedRoot contains a component which is the virtual top-level component.
// It uses the initialisation data and can be sure that it won't change (a guarantee you don't have with component props).
// It's the only component to have state.
// The state can applies to the entire SPA, all routes.
// It gets told by the router which page to render.
// It can house logic that applies when certain pages change to certain other pages.
// 3. LoadedRoot is passed to Routes.routerConfig.
// Routes.routerConfig creates a config that sends all routes to the LoadedRoot component, using the Page & RouterCtl as props.
View BinCodecGeneric.scala
package shipreq.webapp.base.protocol
import boopickle._
object BinCodecGeneric extends BasicImplicitPicklers with TuplePicklers {
@inline implicit class PicklerExt[A](private val p: Pickler[A]) extends AnyVal {
// ...
japgolly / boopickle.scala
Last active Oct 23, 2017
Fixpoint type serialisation
View boopickle.scala
// Can't use the usual morphisms, cata = depth-first, ana = breadth-first evaluation order.
// You'd think there'd be a way to describe the effects and execute them in different order but I stopped trying.
def pickleFix[F[_]: Functor](implicit p: Pickler[F[Unit]]): Pickler[Fix[F]] =
new Pickler[Fix[F]] {
override def pickle(f: Fix[F])(implicit state: PickleState): Unit = {
// val fUnit = Functor[F].void(f.unfix)
// p.pickle(fUnit)
// Functor[F].map(f.unfix)(pickle)
japgolly / min.css
Created Oct 15, 2017
Sample ScalaCSS > 26
View min.css
._b0{color:#000}._b2{color:#c00}._b3 svg{max-width:100%}._b4{width:24px !important;text-align:center !important}._b5{padding-bottom:1rem;padding-top:0.5rem}._b6:first-child{margin-top:0 !important}._b6:not(:first-child){margin-top:1.8em !important}._b6{margin-bottom:0.2em !important;padding-top:0.8em !important;padding-bottom:0.3em !important}._b7{margin-top:0 !important}._b8{cursor:pointer}._b9{text-align:center;padding-top:2.7em !important;height:6.8em !important;-moz-flex-grow:0 !important;-webkit-flex-grow:0 !important;-ms-flex-grow:0 !important;-o-flex-grow:0 !important;flex-grow:0 !important}._ba{font-size:3rem !important}._bb{border-color:red !important}._bc{margin-bottom:1em}._bc tr:nth-child(odd) td._s{background-color:#fffde8}._bc tr:nth-child(even) td._s{background-color:#def2fc}._bc tr:nth-child(odd) td._d{background-color:#fcf8e3}._bc tr:nth-child(even) td._d{background-color:#d9edf7}._bd{font-family:monospace;background-color:#fff}._be{font-family:monospace;white-space:nowrap;color:#f39}._bf{t
View CallbackReusability.scala
import japgolly.scalajs.react._
import japgolly.scalajs.react.extra._
import japgolly.scalajs.react.vdom.html_<^._
object NotReusable {
final case class Props(name: String, update: Callback)
final class Backend($: BackendScope[Props, Unit]) {
def render(p: Props): VdomElement =
View blog-201706.scala
sealed trait Field {
type Value
def fold[F[_]](f: Field.Fold[F]): F[Value]
object Field {
case object Name extends Field {
override type Value = String
override def fold[F[_]](f: Field.Fold[F]): F[Value] =
japgolly /
Last active Apr 27, 2017
NodeJS + Scala.JS
npm config set prefix ~/.npm
npm install -g jsdom source-map-support yarn
export NODE_PATH="$(npm config get prefix)"/lib/node_modules
export PATH="$PATH:$(npm config get prefix)/bin"

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I hereby claim:

  • I am japgolly on github.
  • I am japgolly ( on keybase.
  • I have a public key ASA2mh3TjdvZuvSBDifylawPHaTJDuBE4NQhXtZR8vhF4Ao

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View ReactCollapse.scala
import japgolly.scalajs.react._
import scalajs.js.{undefined, Dictionary, Dynamic, Object, UndefOr}
import shipreq.base.util.Memo
import ReactCollapse._
* Component-wrapper for collapse animation with react-motion for elements with variable (and dynamic) height.
View JsEnvUtils.scala
import scala.util.Try
object JsEnvUtils {
/** Sample (real) values are:
* - Mozilla/5.0 (Unknown; Linux x86_64) AppleWebKit/538.1 (KHTML, like Gecko) PhantomJS/2.1.1 Safari/538.1
* - Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0
* - Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.75 Safari/537.36
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