Update README.md

Author: tonyfreeman

README.md

@@ -1,17 +1,39 @@
 # JavaScript
 
-Linux version of JavaScriptCore written in Swift with closure support.
+This package provides JavaScript APIs for several engines.
+
+## Package Targets
+* JavaScipt - common protocols
+* V8 - google's v8 engine wrapper
+* JavaScriptCoreSwift - linux version of apple's JavaScriptCore
+* СhakraCore - microsoft's chakracore engine wrapper (WIP)
+
+## Package.swift
+
+```swift
+.package(url: "https://github.com/tris-foundation/javascript.git", .branch("master"))
+```
 
 ## Requirements
 
+### V8
+
+#### macOS
 ```bash
-apt install libjavascriptcoregtk-1.0-dev
+brew install v8
 ```
 
-## Package.swift
+#### Linux
+```bash
+add-apt-repository -y ppa:pinepain/libv8-archived
+apt update && apt install -y libv8-dev
+```
 
-```swift
-.package(url: "https://github.com/tris-foundation/javascript.git", .branch("master"))
+### JavaScriptCore
+
+#### Linux
+```bash
+apt install -y libjavascriptcoregtk-1.0-dev
 ```
 
 ## Usage
@@ -28,3 +50,29 @@ assertTrue(result.isString)
 assertEqual(try result.toString(), "result string")
 assertEqual("\(result)", "result string")
 ```
+
+## Useful commands
+
+### macOS
+```bash
+swift package \
+ -Xcc -I/usr/local/include \
+ -Xlinker -L/usr/local/lib \
+ -Xlinker /usr/local/lib/libv8.dylib \
+ -Xlinker /usr/local/lib/libv8_libbase.a \
+ -Xlinker /usr/local/lib/libv8_libplatform.a \
+ generate-xcodeproj
+
+swift test \
+ -Xlinker /System/Library/Frameworks/JavaScriptCore.framework/Versions/Current/JavaScriptCore \
+ -Xcc -I/usr/local/include \
+ -Xlinker /usr/local/lib/libv8.dylib \
+ -Xlinker /usr/local/lib/libv8_libbase.a \
+ -Xlinker /usr/local/lib/libv8_libplatform.a \
+ --generate-linuxmain
+```
+
+### Linux
+```bash
+swift test -Xlinker /usr/lib/libv8_libbase.a -Xlinker /usr/lib/libv8_libplatform.a
+```