ecmascript

The public classes are Parser, Script, and ScriptClosure. Parser is the main entry to the compiler. Script contains a compiled script. ScriptClosure lets programs execute the global script and then call back into the JavaScript. The other classes are public only because JavaScript gets compiled to Java. The generated Java classes need to access the JavaScript libraries.

The script must first be compiled to a Script object, then executed. The following example gives the bare-bones script invocation.

Parser parser = new Parser();
Script script = parser.parse("foo.js");
script.execute(null, null);

You can make Java objects available to the Script by adding them to a HashMap. For example, the File object. The running script will see these objects as properties of the Global object. If you set the 'out' object, the script can use 'writeln("foo")' to write to 'out'.

HashMap map = new HashMap();
map.put("File", Pwd.lookup());
map.put("out", System.out);
map.put("myObject", myObject);

script.execute(map, null);

You can also make any Java object be the global prototype. Essentially, the effect is similar to the HashMap technique, but it's a little simpler.

The Script object is threadsafe. It's safe to execute the same script in multiple threads.

The ScriptClosure object, of course, is not threadsafe.

Most applications will use the Parser.parse(String) interface to parse JavaScript. That method will try to load a precompiled script from the work directory before trying to parse it.

Applications will often set the script path a directory for script and include the classpath in the path. Applications will often override the work dir for a more appropriate work directory.

package com.caucho.vfs.*;
package com.caucho.es.*;

...

com.caucho.es.parser.Parser parser;
parser = new com.caucho.es.parser.Parser();

MergePath scriptPath = new MergePath();
scriptPath.addMergePath(Vfs.lookup("/home/ferg/js"));
scriptPath.addClassPath(loader);
parser.setScriptPath(scriptPath);
 
Path workPath = Vfs.lookup("/tmp/caucho/work");
parser.setWorkDir(workPath);
 
Script script = parser.parse("test.js");