Writing Native JavaScript Methods

JSNI methods are declared native and contain JavaScript code in a specially formatted comment block between the end of the parameter list and the trailing semicolon. A JSNI comment block begins with the exact token /*-{ and ends with the exact token }-*/. JSNI methods are be called just like any normal Java method. They can be static or instance methods.

Example

public static native void alert(String msg) /*-{
  $wnd.alert(msg);
}-*/;
Tip
In hosted mode, you can set a breakpoint on the source line containing the opening brace of a JSNI method, allowing you to see invocation arguments.