add lightweight fetch-based http request-transport for the browser (#244

)

* add lightweight fetch-based http request-transport for the browser

* readme

README.md

@@ -299,6 +299,25 @@ val api: MyApi[fs2.Stream[IO, *]] = client.wire[MyApi[fs2.Stream[IO, *]]]
 
 ```
 
+### fetch (browser)
+
+This is useful when running in the browser, because it will have a smaller bundle-size then using the http4s client.
+
+Use with:
+```
+libraryDependencies += "com.github.cornerman" %%% "sloth-jsdom-client" % "0.7.3"
+```
+
+In the client:
+```scala
+import sloth.Client
+import sloth.ext.jsdom.client.HttpRpcTransport
+
+// for usual rpc
+val client = Client[String, IO](HttpRpcTransport[IO])
+val api: MyApi[IO] = client.wire[MyApi[IO]]
+```
+
 ## Experimental: Checksum for Apis
 
 Currently scala-2 only.

build.sbt

@@ -75,6 +75,19 @@ lazy val sloth = crossProject(JSPlatform, JVMPlatform)
       Nil
   ).jsSettings(jsSettings)
 
+lazy val jsdomClient = project
+  .enablePlugins(ScalaJSPlugin)
+  .dependsOn(sloth.js)
+  .settings(commonSettings)
+  .settings(jsSettings)
+  .settings(
+    name := "sloth-jsdom-client",
+    libraryDependencies ++=
+      Deps.scalaJsDom.value ::
+      Deps.catsEffect.value ::
+      Nil
+  )
+
 lazy val http4sClient = crossProject(JSPlatform, JVMPlatform)
   .crossType(CrossType.Pure)
   .dependsOn(sloth)

jsdomClient/src/main/scala/HttpRpcTransport.scala

@@ -0,0 +1,27 @@
+package sloth.ext.jsdom.client
+
+import cats.effect.Async
+import cats.implicits._
+import sloth.{Request, RequestTransport}
+import org.scalajs.dom
+
+import scala.scalajs.js
+import scala.scalajs.js.JSConverters._
+
+case class HttpRequestConfig(
+  baseUri: String = "/",
+  headers: Map[String, String] = Map.empty,
+)
+
+object HttpRpcTransport {
+  def apply[F[_]: Async]: RequestTransport[String, F] = apply(HttpRequestConfig().pure[F])
+
+  def apply[F[_]: Async](config: F[HttpRequestConfig]): RequestTransport[String, F] = new RequestTransport[String, F] {
+    override def apply(request: Request[String]): F[String] = for {
+      config <- config
+      url = s"${config.baseUri}${request.path.mkString("/")}"
+      requestArgs = new dom.RequestInit { headers = config.headers.toJSDictionary; method = dom.HttpMethod.POST; body = request.payload }
+      result <- Async[F].fromThenable(Async[F].delay[js.Thenable[String]](dom.fetch(url, requestArgs).`then`[String](_.text())))
+    } yield result
+  }
+}

project/Deps.scala

@@ -9,6 +9,7 @@ object Deps {
 
   val scalaReflect = dep("org.scala-lang" % "scala-reflect")
   val cats = dep("org.typelevel" %%% "cats-core" % "2.12.0")
+  val catsEffect = dep("org.typelevel" %%% "cats-effect" % "3.5.4")
   val chameleon = dep("com.github.cornerman" %%% "chameleon" % "0.4.1")
 
   val zioJson = dep("dev.zio" %%% "zio-json" % "0.7.0")
@@ -27,4 +28,6 @@ object Deps {
     val dsl = dep("org.http4s" %%% "http4s-dsl" % version)
     val client = dep("org.http4s" %%% "http4s-client" % version)
   }
+
+  val scalaJsDom = dep("org.scala-js" %%% "scalajs-dom" % "2.8.0")
 }