Program/ Example of Nashorn Javascript (js) Engine in Java 8 >
Find square of number using javascript (js) squareFunction
package nashorn1;
import java.io.FileReader;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
public class Nashorn_calculateSquareOfNumberInJavascriptFunction {
public static void main(String[] args) throws Exception {
System.out.println("In java - START");
// Get nashorn javascript engine
ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
// Pass the location of js file
//engine.eval(new FileReader("E:/pocJmse/myNashornJavaScript.js"));
//OR
engine.eval("load('E:/pocJmse/myNashornJavaScript.js')");
// NashornScriptEngine implements Invocable interface
Invocable invocable = (Invocable) engine;
// Call/Invoke js (javascript) function - Find square of number using js squareFunction
System.out.println("In java - Call js (javascript) squareFunction to - Find square of number");
Object squareResult = invocable.invokeFunction("squareFunction", 2);
System.out.println("In java - squareResult = " + squareResult);
System.out.println("In java - squareResult type = " + squareResult.getClass());
System.out.println("In java - FINISH");
}
}
/* OUTPUT
In java - START
In myNashornJavaScript.js
End myNashornJavaScript.js
In java - Call js (javascript) squareFunction to - Find square of number
In js function - Object type = [object Number]
In js function - Calulating square of 2
In java - squareResult = 4.0
In java - squareResult type = class java.lang.Double
In java - FINISH
*/
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E:/pocJmse/myNashornJavaScript.js looks like this >
print('In myNashornJavaScript.js');
var squareFunction = function(num) {
print("In js function - Object type = " + Object.prototype.toString.call(num));
print('In js function - Calulating square of ' + num);
return (num * num);
};
print('End myNashornJavaScript.js');
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