Use instance fields and properties from NodeJs package in JavaScript app

This article provides an introduction to cross-technology handling of static fields and properties.
Javonet allows you to reference and use modules or packages written in (Java/Kotlin/Groovy/Clojure, C#/VB.NET, Ruby, Perl, Python, JavaScript/TypeScript) like they were created in your technology. If have not yet created your first project check Javonet overview and quick start guides for your technology.

With Javonet you can interact with instance field and properties from NodeJs package like they were available in JavaScript but invocation must be performed through Javonet SDK API.

Javonet allows you to pass any JavaScript value type as argument to method from NodeJs package. For reference type arguments (instances of other classes) you can create such instance with Javonet and pass the Invocation Context variable referencing that object as argument of method invocation.

Custom NodeJs package with instance fields and properties

With Javonet it is possible to reference any custom NodeJs package and interact with public instance fields and properties declared on types defined within that module almost the same as with any other JavaScript library.

Snippet below represents the sample code from NodeJs package which contains class with fields:

const fs = require('fs').promises;

class TestClass {

    publicValue;
    #privateValue;
    static staticValue = 3;
    
    constructor(first, second) {
    	this.publicValue = first;
    	this.#privateValue = second;
    }
}

module.exports = TestClasspublicValue;
#privateValue;
static staticValue = 3;

constructor(first, second) {
	this.publicValue = first;
	this.#privateValue = second;
}

It is possible to get one of the declared instance fields from NodeJs package using following JavaScript code.

This uses in memory runtime bridging to load the NodeJs package, and next retrieves reference to specific type and gets the instance field. Result of the invocation is returned as regular JavaScript value and can be used for further processing. It is possible to set one of the declared instance fields from NodeJs package using following JavaScript code.

This uses in memory runtime bridging to load the NodeJs package, and next retrieves reference to specific type, then sets and gets the instance field. Result of the invocation is returned as regular JavaScript value and can be used for further processing.

Framework instance fields and properties

The same steps are required to get types and fields from framework NodeJs package:

The same operation can be performed remotely by just changing the new Runtime Context invocation from in memory to tcp that will create and interact with your NodeJs package objects on any remote node, container or service that hosts Javonet Code Gateway. This way you can preserve the same logic in your application and instantly switch between monolithic and microservices architecture without the need to implement the integration layer based on web services or other remote invocation methods.

Read more about use cases and software architecture scenarios where Javonet runtime bridging technology can support your development process.