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Suppose I have a Javascript file
function js_main(args){
/* some code */
var x = api_method1(some_argument);
/* some code */
}
And I try to run it with javax.scripting the usual way
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("javascript");
engine.eval(...);
Now the I'd like to handle the call to api_method1 in Javascript with my Java class. I'd like to have some kind of mapping/binding of calls i.e. each time the script calls api_method1(arg) a method
public Object api_method1(Object arg){ ... }
(placed in the same class as the engine) would be called.
Can I achieve this?
788
The bind() method creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called.
JavaScript Function bind() With the bind() method, an object can borrow a method from another object. The example below creates 2 objects (person and member).
The call, bind and apply methods can be used to set the this keyword independent of how a function is called. The bind method creates a copy of the function and sets the this keyword, while the call and apply methods sets the this keyword and calls the function immediately.
. bind() is used when you need to pass a callback (e.g. some sort of function reference), but you want the caller to call your function with a specific this value.
engine.createBindings() to make a Bindings object;put an object exposing your method into the bindings with some name:
Bindings b = engine.createBindings(); b.put("api", yourApiObject); engine.setBindings(b, ScriptContext.ENGINE_SCOPE); Then in JavaScript there'll be a global "api" object you can call:
api.method1( "foo", 14, "whatever" ); The facility is easy to use, but be careful with what you pass back and forth; it doesn't do that much to convert JavaScript types to Java types.
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