One language end to end
The same language on the interface and the server side, with Next.js, Nuxt or Node.js. Data types can be shared between the front end and the API, which limits discrepancies between the two.
Expertise · JavaScript & TypeScript
JavaScript / TypeScript Development: reliable web applications
Etixio delivers JavaScript / TypeScript development for your web applications: interfaces, APIs and services, with structured code, explicit data contracts and consistent development tooling. We build new products, take over existing ones and add AI features to them, from the assistant interface to the service that orchestrates the models.
Understanding the technology
JavaScript & TypeScript in your project.
JavaScript is used for web interactions and in server-side environments. TypeScript adds a static description of types to make code interfaces more explicit. Together, they make it possible to share one language across several layers of the product, without erasing the different responsibilities of the browser and the server.
The strengths for your product
Why choose JavaScript / TypeScript?
JavaScript is the language of the browser; TypeScript has become its natural complement for applications that need to last. Together they cover rich interfaces, APIs and services, with a broad ecosystem and an active community.
Typing for complex projects
TypeScript makes code contracts explicit, eases refactoring and helps a team take over code it did not write.
A broad ecosystem
npm libraries, UI frameworks, testing and build tools cover most needs, provided dependencies are chosen and monitored carefully.
Controllable performance
Server-side or static rendering, code splitting, lazy loading and caching keep load times in check; Node.js handles I/O-heavy applications well.
Our scope of work
The work we take on.
Contracts
Use types to make exchanged data and code interfaces explicit.
Web applications
Build interactions, network calls and interface states.
Tooling
Organize compilation, tests, code analysis and dependency management.
We build single-page applications (SPAs), progressive web apps (PWAs), server-rendered or static applications (SSR/SSG) and REST APIs, as well as gradual migrations from JavaScript code to TypeScript.
Our JavaScript / TypeScript expertise
The JavaScript / TypeScript stack we master.
Front end
React, Vue.js, Angular and Next.js for interfaces, from business dashboards to SaaS products.
Back end
Node.js, Express, NestJS and Fastify for APIs, services and background processing.
Data
PostgreSQL, MongoDB and Redis depending on the nature of the data, with versioned schemas and migrations.
Cloud & deployment
Docker, Vercel and AWS Lambda for reproducible environments and automated deployments.
JavaScript / TypeScript and AI
AI interfaces and services in TypeScript.
An AI feature in a web product depends as much on the interface as on the model: streaming responses, conversation history, source citations, error recovery, human validation before an action. On the server side, a Node.js or NestJS service orchestrates model calls, agent tools, access rights and logs.
We build both layers in TypeScript, with shared types and tests, and also take over AI prototypes to bring them to production. See our AI agents and chatbots and our enterprise AI solutions.
In the field
From technology to real-world use.
On a subscription flow, we define the form data, the API responses and the interface states. Types help spot inconsistencies during development; runtime validation remains necessary for data received over the network. Errors are handled within the flow rather than left to a technical message.
The choices that matter
The choices to examine before building.
Typing does not guarantee that a business rule or an external response is valid. We limit the escape hatches that hide errors and organize contracts between components. The build chain, dependencies and tests must remain reproducible for every developer.
From work to deliverables
Delivery your team can take over.
The scope of the engagement specifies the components to build or take over and the acceptance criteria. We work in short releases, with continuous integration and code reviews, then handle the production release and maintenance. We prepare what is needed to understand the changes, verify them and continue the work.
- Documented components and states
- Interfaces connected to APIs
- User journey tests
Frequently asked questions
JavaScript / TypeScript development: your questions.
What is JavaScript / TypeScript and why use it?
JavaScript is the language run by browsers, also used on the server side with Node.js. TypeScript is a superset of JavaScript that adds static typing. Together, they make it possible to build rich interfaces, APIs and services with a single language.
Is TypeScript suited to enterprise applications?
Yes. Static typing makes code contracts explicit and eases maintenance and handover to another team. It is now the common choice for web applications that need to evolve over several years.
Which front-end framework should you choose between React, Vue and Angular?
React for flexibility and the breadth of its ecosystem, Vue for its gradual learning curve, Angular for highly structured enterprise applications. The choice depends on the product’s complexity, your team’s skills and the expected maintenance.
Can Node.js replace Java or Python on the server side?
In many cases, yes, particularly for APIs, real-time applications and I/O-heavy services. For intensive computation or an existing Java or Python ecosystem, another choice may remain preferable. We recommend the stack based on your context.
What is the difference between SPA, PWA and SSR?
A SPA is a single-page application that updates without reloading the page. A PWA is an installable web application that can partly work offline. SSR generates pages on the server, which improves SEO and initial rendering. The choice depends on SEO, usage and expected performance.
How do you secure a JavaScript application?
Input validation, escaping of displayed content, HTTPS, rigorous token management and regular dependency audits (npm audit or equivalent tools). See our article on securing a React application.
How do you manage state in a complex JavaScript application?
Depending on the need, with React Context, Zustand or Redux Toolkit, and libraries dedicated to server data. We favor typed state, limited to what is actually shared between screens.
Can an AI assistant be added to an existing web application?
Yes. The assistant is integrated as an interface component, connected to a server-side service that calls the model with the user’s permissions. We handle response streaming, error management, logs and the evaluations required for production.
What collaboration models do you offer?
A fixed-price project for a defined scope, a dedicated team to evolve your product over time, or a targeted engagement, such as a migration to TypeScript.
Let’s talk about your technical context.
Tell us about the application, the issue to address and the known constraints. We will review the dependencies and the first scope of work with your team.