Unreal.js is a plug-in which brings V8-powered Javascript into UnrealEngine4.

• Powered by latest V8 (ES6)

• CommonJS modules

• Full access to the whole UnrealEngine API

• Free to subclass existing classes including blueprint

• Web-dev like UMG (Jade, pseudo-css, pseudo-angular.js)

• Live reload

• Communicate with outer world: REST, process(pipe), arraybuffer, ...

• Bridge API for editor extension

• Auto-completion for Visual Studio (auto-generated *.d.ts)

• Dedicated Javascript console on UnrealEditor

  

• (Full) access to existing javascript libraries via npm, bower, ...

  

• Install git-lfs first to download *.umap, *.uasset properly. (https://git-lfs.github.com/)
• Download prebuilt V8 and unzip into Engine/Plugins/UnrealJS. (files are located in releases)
• Open Examples/JavascriptPlayground.uproject

Apache2

• https://github.com/gabrielecirulli/2048

  

let myActor = new Actor(GWorld,{X:10,Y:20,Z:30});
myActor.SetActorLocation({X:40,Y:80,Z:120});

class MyActor extends Actor {
  properties() {
    this.MyProp/*EditAnywhere+Replicated+int*/;
  }
  RPC(x/*int*/) /*Server+Reliable*/ {
    console.log('This function is replicated',this.MyProp++);
  }
}
let MyActor_C = require('uclass')()(global,MyActor);
if (GWorld.IsServer()) { 
  new MyActor_C(GWorld);
}

let _ = require('lodash');
let kick = () => {
  console.log("Hello timer!",_.keys(this));
  setTimeout(kick,1000);
};
kick();

div
	span.full
		Button.full
			text {{text}}
		div.full
			Button.full(fn.on-clicked="inc()")
				text {{count}}
			Button.full(fn.on-clicked="add()")
				text Click button above!
	span
		text.yellow >
		EditableText(Binding.Text='text',
			fn.on-text-changed='text = ^arguments[0]',
			HintText="Your secret goes here")
		
	list.full(repeat='item in items',on-click="discard(item)") 
		HorizontalBox.small
			text.full {{item.key}}
			text.full {{item.value}}

Just add some static function into your UBlueprintFunctionLibrary.

UCLASS()
class UMyBlueprintFunctionLibrary : public UBlueprintFunctionLibrary
{
    GENERATED_BODY();
public:
    UFUNCTION(BlueprintCallable, Category = "Scripting | Javascript")
    static bool MySuperFunction(UMySuperActor* SuperActor, FString SuperPath, FVector* OutVector);
};

let result = MySuperActor.MySuperFunction("SuperPath")
console.log(`return value:${result.$} vector:${result.OutVector}`)

let ab = new ArrayBuffer(32*1024); // 32K bytes buffer
let u8 = new Uint8Array(ab); // typed array
memory.bind(ab);
GWorld.MySuperMemoryFunction();
memory.unbind(ab);

void UMyBlueprintFunctionLibrary::MySuperMemoryFunction(UWorld* World)
{
    auto size = FArrayBufferAccessor::GetSize();
    auto buffer = FArrayBufferAccessor::GetData();
}