konsoletyper/teavm 0.10.0 on GitHub

Improvements to native JavaScript interaction

Exporting declarations from Java to JavaScript

This long expected feature is finally delivered by this release. Now TeaVM can not only take standard Java main classes with main methods, but also module classes. Instead of main method, they can declare static methods annotated with @JSExport.
These methods will be exported from generated TeaVM module (or rather as top-level declarations in non-module output).

Additionally, @JSExport annotation can be used to mark methods of classes that should be available in JS. See full documentation in Creating JavaScript modules section.

Generating modules

From this release, TeaVM can produce ES2015 modules. Moreover, there's a new build parameter that allows to specify module type (CommonJS, ES2015, UMD, immediately-invoked function).

Importing constructors

Previously, to declare a constructor for a JS class, you had to define static factory method, annotated with @JSBody and some JS within. Now, it's possible to declare a non-abstract overlay class (should be additionally annotated with @JSClass) with constructors. To instantiate such classes, you can use new syntax, as you used for normal Java classes.

Importing static and top-level methods

Since this release, you can define static native methods of overlay classes without extra annotations. These methods will be automatically mapped to corresponding static JS methods.

You can also put @JSTopLevel annotation on such methods so that they aren't mapped to static methods of containing classes, but to top-level methods.

Support `instanceof`

Overlay classes now properly support instanceof and casts (in strict mode). Note that instanceof is not available for interfaces (i.e. as previously, always produces true). Support of instanceof can be disabled for classes by applying @JSClass(transparent = true).

Importing declarations from external modules

You can also use @JSModule annotation to import declarations from JS modules. Following cases possible:

@JSModule on class – imports class
@JSModule and @JSTopLevel – imports function
@JSModule, @JSTopLevel and @JSProperty – imports property

Support varargs

Varargs methods of overlay classes now automatically mapped to varargs methods in JS.

Improved string representation

This release has changed the way java.lang.String represented internally. Instead of array of char, java.lang.String now contains field of native JS string. This can improve performance in some cases, most likely in calls to native JS methods. Previously, to convert java.lang.String to and from JS method, a full copy should have been made. Now, TeaVM only wraps/unwraps JS string with java.lang.String implementation, which is much faster.

This also improves debugging experience. Previously, if you open a java.lang.String value in browser dev tools, you had a object, which has a field, which is an object in turn, which wraps UInt16Array. Now, you only have to deal with one level of indirection (object that has a field), and an actual representation is not array of char codes, but JS string, easily readable in dev tools.

ES2015 modules

Since this release, TeaVM generates ES2015 output, not ES5. This allows not only to support ES2015 modules, but reduces output side thanks to arrow function syntax.

Class library emulation

String.toLowerCase/toUpperCase methods that take Locale parameter
chars and codePoints methods in CharSequence
String.format/Formatter.format now support more format specifiers
Math methods for arithmetic operations that throw exception on overflow
OutputStream.nullOutputStream
SecureRandom
BigInteger.sqrt
WeakHashMap
CopyOnWriteArrayList
Fair support of ThreadLocal in green threads
Support @Inherited annotations
PrintStream implements Appendable
BufferedReader.lines method

Gradle plugin improvements

Improve source file resolution when generating source maps in Gradle
Add tasks to start/update and stop development server

Other stuff

Overlay class for JS Promise (JSPromise class)
Support @Inherited annotations
New convention for event registration in standard overlay classes (onEventName returning Registration to unbind the listener, instead of listenEventName/neglectEventName).

Sponsorship

Worth mentioning that TeaVM evolved with the support from its sponsors. If you like this project, you can start donating.

Special thanks to @reportmill and @shannah, our permanent sponsors!