Scalajs+

This repository contains handy macros , facades for upcoming javascript features(not finalized yet), polyfills when they make sense and some useful misc stuff.

// build.sbt
resolvers += Resolver.bintrayRepo("scalajs-plus", "maven")
libraryDependencies += "scalajs-plus" %%% "core" % "replaceThisWithLatestVersionNumberFromReleaseTags"
//works with scalajs >= 1.0.0-M2 and supports only scala 2.12

Docs

• Macros
• Facades
• Polyfills
• Misc

Macros

• FunctionObjectMacro

FunctionObjectMacro

converts scala function parameters to javascript literal object.

  def point(x:Int,y:Int,z:js.UndefOr[Int] = js.undefined) : js.Object = {
    val p = FunctionObjectMacro()
    p.asInstanceOf[js.Object]
  }
  
  val p = point(1,1)  // {x:1,y:1} 
  
  val p = point(1,1,1) // {x:1,y:1,z:1}

Renaming Params

  def voltage(i:Double,@rename("resistance")r:Double) : js.Object = {
    val v = FunctionObjectMacro()
    v.asInstanceOf[js.Object]
  }
  
  val v1 = volate(i = 2,r = 100) // {i: 2,resistance:100}

Excluding Params

 
 def energy(@rename("mass") m:Double,c:Double,@exclude debug:Boolean):js.Object = {
    if(debug) // do something
    val e = FunctionObjectMacro()
    e.asInstanceOf[js.Object]
 }
 
 val e = energy(m = 74,c = 3.18,debug = false) // {mass:74,c:3.18}
 

Facades

• Observable

Observable

Facade for :https://github.com/tc39/proposal-observable (Ref Impl : https://github.com/zenparsing/zen-observable)

Polyfills

• Object.assign

Object Assign

Polyfill for js.Object.assign

Example

   val target = js.Dynamic.literal(id = 1, name = "hello")
   val source1 = js.Dynamic.literal(id = 2, name2 = "hello2")
   val source2 = js.Dynamic.literal(name = "hello3", age = 20)
   
   val combine = ObjectAssign(target, source1, source2) // {id:2,name:"hello3",name2:"hello2",age:20}

Misc

• OptionalParam
• ReadonlyArray
• UnionTypeToJSAnyImplicit

OptionalParam

Inline version of js.UndefOr[] , mostly used in conjunction with FunctionObjectMacro. More Details : scala-js/scala-js#2714

Example

 def fun(value: OptionalParam[Int] = OptDefault) = value

    expect(fun(2)).toEqual(OptSpecified(2).asInstanceOf[js.Any])
    expect(fun()).toBe(OptDefault)

ReadonlyArray

Readonly version of js.Array

Example

val a:ReadonlyArray[Int] = ReadonlyArray(1,2,3)

a.length //compiles fine 

a.push() // coompile error 

UnionType To JSAny Implicit

Blindly casts scalajs union type to js.Any

Example

 
 val id : String | Int = 3
 
 val o = js.Dynamic.literal(id = id) // compile error 
 
  import scalajsplus.DangerousUnionToJSAnyImplicit._ //error gone 
  
  //Nit : make sure that scope of this import as least as possible