Importing JavaScript from other file/npm package throws error

[TheGreatViolet]

Hey there! I've been trying to migrate my project from J2V8 to Javet for a while now. However a bit of a snag I've hit is that when I try to import JS code from another file/from a package such as axios, Javet throws an error along the lines of:

com.caoccao.javet.exceptions.JavetExecutionException: Error: Cannot find package './importTestModule.js'

I'm just wondering if this could be something I'm doing wrong or if Javet doesn't support this or if it could be something different entirely. I've read through the documentation and other issues/discussions to try to find an answer to no avail. I'd be happy to share more code if needed to. Thanks!

[caoccao]

May I know which mode you are using?

V8 Mode

You need to register a module resolver via v8Runtime.setV8ModuleResolver(...). Please refer to this test suite for detail.

Node.js Mode

You need to follow some rules to make it work. Please refer to #148 for detail.

[caoccao]

Also, are you trying that on Android? There is no Node.js mode for Android.

[TheGreatViolet]

Ok I fixed the runtime so now it doesn't throw the NullPointerException now, however now it throws the Error: Cannot find package './importTestModule.js' from before. Here's my code now:

NodeRuntime setupRuntime() throws JavetException {
        JavetEngineConfig config = new JavetEngineConfig();

        config.setJSRuntimeType(JSRuntimeType.Node);

        JavetEnginePool<NodeRuntime> pool = new JavetEnginePool<NodeRuntime>(config);

        pool.getConfig().setJSRuntimeType(JSRuntimeType.Node);

        NodeRuntime runtime = pool.getEngine().getV8Runtime();

        runtime.getNodeModule(NodeModuleModule.class).setRequireRootDirectory(getResourceFile("jsTests").getAbsolutePath());

        return runtime;
    }

And here's the test I'm using the runtime in:

@Test
    @DisplayName("Can run JS with imports")
    void runJSWithImports() {
        try (NodeRuntime runtime = setupRuntime()) {
            runner = new JSExecutionInterface(getResourceFile("jsTests/importTest.js"), runtime);
            runner.runtime.await();
            assertDoesNotThrow(() -> runner.registerAndRun());
        } catch (JavetException e) {
            BlockJS.instance.getLogger().log(Level.SEVERE,
                    "There was an error creating the Javet runtime.");
            throw new RuntimeException(e);
        }
    }

To answer your other question, no I'm not running this on Andrioid, I'm running it on Linux.

[caoccao]

V8 Mode

You need to register a module resolver via v8Runtime.setV8ModuleResolver(...). Please refer to this test suite for detail.

[TheGreatViolet]

Setting the module resolver totally worked! Here's the code I ended up with for the module resolver:

@Test
    @DisplayName("Can run JS with imports")
    void runJSWithImports() {
        try (NodeRuntime runtime = setupRuntime()) {
            runtime.setV8ModuleResolver(((v8Runtime, resourceName, iv8Module) -> {
                if (resourceName.equals("./importTestModule.js")) {
                    return runtime.getExecutor(getResourceFile("jsTests/importTestModule.js"))
                            .setResourceName(resourceName)
                            .compileV8Module();
                } else {
                    return null;
                }
            }));

            runner = new JSExecutionInterface(getResourceFile("jsTests/importTest.js"), runtime);
            runner.runtime.await();
            assertDoesNotThrow(() -> runner.registerAndRun());
        } catch (JavetException e) {
            BlockJS.instance.getLogger().log(Level.SEVERE,
                    "There was an error creating the Javet runtime.");
            throw new RuntimeException(e);
        }
    }

Thanks so much for your help in resolving this issue, I've been stuck on it for weeks.

[caoccao]

Great to see that working. And thank you for sharing the solution with the community.

[zahrahariry]

I have the same problem. With the difference that I have to add a module not just single file . Thank you for your guidance.
i have to use v8 mode not Node.js mode.

[caoccao]

It's the same solution. Your module resolver needs to handle the requests respectively just like what Node.js does.