Java Requires Chilkat v11.4.0+

Call a JavaScript Function Returning an Integer

See more JavaScript Examples

Demonstrates how to call a JavaScript function that returns an integer. Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Js;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

    public static void main(String[] args) {
        // ----------------------------------------------------------------------------------
        // The Javascript function called in this example is shown at the bottom of this page.
        // -----------------------------------------------------------------------------------

        // In this example, we'll load the Javascript function definition from a file.
        // It doesn't need to come from a file.  It could just as easily be loaded from a string.
        StringBuilder sbScript = new StringBuilder();
        try {
            sbScript.loadFile("js_call_function.js", "utf-8");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Note: Each instance of a Chilkat Js object automatically establishes
        // its own internal runtime and context.  Applications do not need to explicitly create
        // the JavaScript runtime or context.
        Js js = new Js();

        JsonObject result = new JsonObject();
        result.setEmitCompact(false);

        // Call Eval to add the function (shown at the bottom of this page) to the context's global object
        try {
            js.eval(sbScript, result);
        } catch (ChilkatException e) {
            // Examine the result for an exception.
            System.out.println(result.emit());

            // Also examine the LastErrorText.
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println(result.emit());

        // The expected output is "undefined":

        // {
        //   "type": "undefined",
        //   "value": "undefined"
        // }

        //    When Eval processes a script containing only a function declaration,
        //    it successfully performs the action (the function becomes defined).
        //    However, since the script consists of a statement that produces no value,
        //    the script's overall completion value is empty. In JavaScript, the
        //    absence of a value is represented by `undefined`.
        //
        //    Therefore, the Eval call returns `undefined`.

        // ------------------------------------------------------------------------------
        // Call the function calculateScore("Player1", 10, 20)

        JsonObject funcCall = new JsonObject();

        // Create JSON defining the function call:

        // {
        //   "name": "calculateScore",
        //   "args": [ "Player1", 10, 20 ]
        // }

        funcCall.updateString("name", "calculateScore");
        funcCall.updateString("args[0]", "Player1");
        funcCall.updateInt("args[1]", 10);
        funcCall.updateInt("args[2]", 20);

        funcCall.setEmitCompact(false);
        System.out.println(funcCall.emit());

        try {
            js.callFunction(funcCall, result);
        } catch (ChilkatException e) {
            // Examine the result for an exception.
            System.out.println(result.emit());

            // Also examine the LastErrorText.
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println(result.emit());

        // Output:

        // {
        //   "type": "int",
        //   "value": 37
        // }

        int retval = result.intOf("value");
        System.out.println("retval = " + retval);
    }
}

JavaScript

function calculateScore(name, pointsA, pointsB) {
    // Return length of name + both scores
    return name.length + pointsA + pointsB;
    }