JavaScript Development Company: Node.js, TypeScript and Vue Builds, Upgrades and Long-Term Maintenance

Updated October 2026 · Written and maintained by the Progression Agency strategy team

A JavaScript development company designs, builds and maintains software written in JavaScript and TypeScript: Node.js back ends and APIs, browser interfaces in Vue or another framework, full-stack web applications and the build, test and deployment tooling around them. We work with product companies, operations teams and agencies that need a JavaScript application built, an aging codebase upgraded or a live system kept patched, and we deliver working software, tests, documentation and a repository you own. Progression Agency is based in New York City and works with clients across the United States and worldwide.

What does a JavaScript development company do?

It turns a business need into software written in JavaScript or TypeScript, then keeps that software secure and current. That spans the server, the browser, the build pipeline and the years of upgrades that follow launch.

What is a JavaScript developer?

A JavaScript developer writes, tests and maintains code in the language MDN describes as lightweight, interpreted or just-in-time compiled, with first-class functions and support for imperative, functional and object-oriented styles. The language is defined by ECMA-262, whose 17th edition, ECMAScript 2026, was published in June 2026.

What do JavaScript developers do day to day?

They build screens and components, write API endpoints and background jobs, connect databases and third-party services, write tests, review each other’s changes, chase down bugs in production, and keep dependencies and runtimes up to date. On a mature product, maintenance and upgrades take as much time as new features.

One language from the browser to the server

JavaScript runs in every browser and, through Node.js, on servers. Teams can share data models, validation rules and some libraries between both sides, which cuts duplicated work and makes it easier for one developer to follow a feature end to end.

JavaScript development services we provide

We build new JavaScript applications, rescue and upgrade existing ones, and run long-term maintenance. Each engagement starts with a written scope and ends with code, tests and documentation in your accounts.

New builds

Most new builds are internal tools, client portals, SaaS products and integration services. We agree a first release that a real user can work with, ship it, then extend it in increments. Our web app development page covers the wider web application practice.

Rescues and takeovers

When a previous team has left, we start with an audit: can it build, can it deploy, what is untested, which packages are abandoned. Then we stabilize before adding anything new, so the first weeks reduce risk instead of adding to it.

Long-term maintenance

JavaScript systems age quickly because runtimes and packages move fast. A maintenance plan schedules Node.js upgrades before end of life, reviews dependency updates weekly and keeps the test suite green, so upgrades never become a rewrite.

Is JavaScript good for web development, and when is it the wrong choice?

Yes, for most web products: it is the scripting language every browser runs natively and it runs on servers through Node.js, so one team can cover the whole application. It is the wrong choice for some heavy computation, data science and systems work, where other languages have the stronger ecosystem.

Why JavaScript is good for web development

Every browser runs it, the npm registry has a package for almost any task, hiring pools are deep, and sharing code between client and server shortens delivery. In the 2025 developer survey run by Stack Overflow, 66 percent of all respondents had used JavaScript in the past year.

When we recommend something else

If the core of the product is data science, we pair a Python service with a JavaScript interface. If the organization runs on the JVM, a Java back end may fit better. If the job is a marketing site, a CMS on our website design and development list costs less than custom code. For PHP estates, see our PHP development and Laravel development pages.

Node JS development company work: APIs, real-time services and back ends

Node.js is where most server-side JavaScript runs. We use it for APIs, integrations, background workers and real-time services, always on a supported long-term support line.

Can JavaScript do back-end work?

Yes. Node.js describes itself as an asynchronous event-driven JavaScript runtime designed to build scalable network applications, in which almost no function performs I/O directly, so the process does not block waiting on the network or disk. It spreads load across CPU cores with child processes and its cluster module.

Which Node.js version should production use?

The Node.js project says production applications should use only Active LTS or Maintenance LTS releases, and that LTS lines typically get critical fixes for 30 months in total. As of October 2026 its release table lists Node.js 22 and 24 as LTS, Node.js 26 as Current, and Node.js 20 as end of life since March 2026.

The Node.js release schedule is changing

Up to Node.js 26, odd-numbered lines were unsupported after six months and even-numbered lines moved to LTS. The project says that from Node.js 27 the cycle becomes annual and every major version moves to LTS after its Current phase. We plan upgrade windows around that calendar.

Express 5 and older Express apps

Express 5 dropped support for Node.js versions before 18 and now passes a rejected promise from async middleware to the error handler, the same as calling next with the error. Upgrading an Express 4 app means checking route patterns and error handling, which we cover with tests before switching.

Is Node.js in demand?

Yes. In the same 2025 survey 48.7 percent of all respondents had used Node.js in the past year, the highest share among the web frameworks and technologies listed. For a buyer, that means a deep pool of people able to maintain what we build. Our back-end development page covers server work in other languages.

TypeScript: types, the native compiler and Node.js type stripping

We write new JavaScript projects in TypeScript unless there is a reason not to. Types catch a large class of mistakes before code runs and make large codebases easier to change safely.

What TypeScript is

The TypeScript project calls it JavaScript with syntax for types. The types are removed at build time and the result is ordinary JavaScript that runs in a browser, on Node.js, Deno or Bun. Nothing is locked in: a TypeScript codebase is a JavaScript codebase with checks added.

TypeScript 7 and faster builds

Microsoft released TypeScript 7.0 on July 8, 2026, a native port of the compiler written in Go that it says typically builds 8 to 12 times faster. It adopts the 6.0 defaults, such as strict mode on, and options deprecated in 6.0, such as an ES5 target, are now errors, so older configurations need updating.

Running TypeScript directly in Node.js

Node.js can now strip types from TypeScript files and run them without a build step; the feature has been on by default since versions 22.18.0 and 23.6.0. It performs no type checking, ignores tsconfig.json and rejects syntax such as enums, so we still run the compiler in CI and use stripping for scripts and tooling.

Vue JS development company work: Vue 3 apps, Nuxt sites and Vue 2 migrations

We build Vue 3 applications and dashboards, server-rendered sites in Nuxt, and move Vue 2 code to supported versions. Vue suits teams that want a gentle learning curve and a framework they can adopt one page at a time.

Why teams pick Vue

Vue describes itself as the progressive framework, designed to be flexible and incrementally adoptable, from enhancing plain HTML to full single-page apps and server rendering. Single-File Components keep a component’s template, logic and styles together, and for full applications Vue recommends the Composition API with those components.

Nuxt for rendered Vue sites

Nuxt calls itself a free and open-source framework for full-stack web apps with Vue. It renders on the server by default, supports static and hybrid output through route rules, and uses the Nitro server engine to build a single output directory that deploys to many hosts.

Vue 2 reached end of life

The Vue team set Vue 2’s end of life for December 31, 2023. It can still be installed, but it receives no more updates, including security patches and browser compatibility fixes, and the Vue team points users who cannot move yet to an extended support offering from a partner. A Vue 2 app in production today needs a migration plan.

Choosing a JavaScript framework for the job

The framework follows the product, the team that will maintain it and the hosting, not fashion. We build with all of the mainstream options and say plainly which one fits.

How we decide

Who will maintain it after launch, what the team already knows, whether pages must rank in search, how interactive the screens are and where it will be hosted. Our React vs Vue vs Angular comparison and web development frameworks guide set out the trade-offs.

Front-end specialists

When the work is mostly interface, design systems and component libraries, our front-end development team leads, with the back end built to match.

Full stack JavaScript development and the MERN stack

Full-stack JavaScript means one language and one type system across the interface, the API and the build. It suits most web products and lets a small team move quickly.

What is a full stack JavaScript developer?

A developer who can build the interface, the API and the database layer of an application in JavaScript or TypeScript, and deploy it. On a well-run project they still specialize: someone owns performance, someone owns security, and reviews cross those lines.

What is MERN stack development?

MongoDB describes MERN as a stack named after MongoDB, Express, React and Node.js, a variation of MEAN, which uses Angular, and it names MEVN, which swaps in Vue. The pattern is a document database, a Node.js API and a JavaScript interface talking JSON end to end.

Is the MERN stack still used?

Yes, widely, though many teams now swap parts: PostgreSQL in place of MongoDB for relational data, Fastify or NestJS in place of Express, Vue or a rendering framework in place of plain React. We treat the stack as a starting point and change any layer that does not fit the data or the team.

Migration and modernization: jQuery, Vue 2, AngularJS and old Node.js

Most JavaScript modernization is incremental: keep the product running, replace parts behind tests and retire the old code page by page. Big-bang rewrites are the riskiest way to modernize and the one we avoid.

jQuery front ends

jQuery is still maintained: jQuery 4.0.0 shipped on January 17, 2026, dropping support for Internet Explorer 10 and older and removing deprecated helpers in favor of native JavaScript. Many sites can simply upgrade; others replace jQuery screen by screen with modern components when the interface needs more than small enhancements.

AngularJS and other end-of-life frameworks

AngularJS applications move to a supported framework, often current Angular; our Angular team handles those migrations. Backbone, Knockout and Ember 1 apps follow the same pattern: wrap, test, replace in slices.

Out-of-support Node.js

Applications on Node.js 20 or older run without upstream security fixes. We upgrade one line at a time, run the test suite on each, and replace packages that do not support the new runtime.

Package security and the npm supply chain

A typical JavaScript application pulls in hundreds of packages, so most of its code was written by people you have never met. Managing that supply chain is part of every build and every maintenance plan we run.

The 2025 npm worm

In September 2025 CISA reported a widespread supply chain compromise of the npm registry: a self-replicating worm known as Shai-Hulud stole developer and cloud credentials and used them to publish malicious code into other packages, affecting more than 500. CISA advised dependency reviews, pinning versions to known safe releases, rotating credentials and phishing-resistant multifactor authentication for developer accounts.

Supply chain is now a top web risk

The OWASP Top 10 for 2025 lists Software Supply Chain Failures as A03, behind only Broken Access Control and Security Misconfiguration. For a JavaScript team that means the package manager, the registry account and the build pipeline are part of the attack surface.

What npm audit does and does not do

The npm audit command sends the dependency tree to the registry and reports known vulnerabilities; the audit-level option sets the severity that fails a build without hiding the rest of the report. It cannot spot a malicious package nobody has reported yet, which is why version pinning and update review still matter.

Testing, performance and accessibility

Every JavaScript project we run has automated tests, measured performance targets and an accessibility standard agreed before the first screen is built. Retrofitting any of the three costs far more than building them in.

Tests at three levels

Unit tests for logic, API tests for every endpoint and browser tests for the flows that make money: sign-up, checkout, the main task a user comes to do. They run on every pull request, so a broken change never reaches staging.

Performance budgets

Google’s Core Web Vitals ask for Largest Contentful Paint within 2.5 seconds, Interaction to Next Paint of 200 milliseconds or less and Cumulative Layout Shift of 0.1 or less, measured at the 75th percentile of page loads. Long JavaScript tasks on the main thread are a frequent reason a web app misses the interaction target.

Accessibility

We build to WCAG 2.2 level AA, which among other things asks for a contrast ratio of at least 4.5:1 for normal text. Custom JavaScript widgets such as menus, dialogs and date pickers need keyboard support and correct roles, so we test them with a keyboard and a screen reader.

JavaScript developers for hire, a staffing firm or a development company: which do you need?

If you need people to direct inside your own team, you are hiring: in-house, through a freelancer platform or through a staffing firm. If you need software delivered and maintained, you are buying from a development company. Progression is a development company: our own team builds and supports the software, and we do not place contractors or recruit for clients.

When to hire JavaScript developers in-house

When the software is the business and will need continuous work for years, an in-house team is usually worth building. A development company can still build the first release and hand it over with documentation, so your hires start on a working codebase.

Should you hire dedicated JavaScript developers through a staffing firm?

It works when you already have a technical lead who will direct them day to day. Without one, extra developers tend to move slowly, because nobody owns architecture, reviews or priorities. Our dedicated developers guide and software development outsourcing guide compare the models in depth.

Before you hire Node JS developers: what to test

Ask candidates to explain the event loop and what blocks it, how they handle errors in async code, how they would upgrade a service across Node.js lines, and how they keep secrets out of a repository. A short paid exercise against a real API tells you more than a quiz.

Before you hire Vue JS developers: what to check

Look for Vue 3 and Composition API experience, comfort with TypeScript in components, Pinia for state, and, if you run Vue 2, someone who has completed a migration. Nuxt experience matters if pages must render on the server.

What JavaScript talent costs on the open market

The Bureau of Labor Statistics puts the median annual wage for software developers at $135,980 and for web developers and digital designers at $99,520, both for May 2025, before benefits, equipment and management time. Published US price bands (market figures, not a Progression rate card) put a dedicated mid-level developer from an agency at $8,000 to $13,000 a month and a senior at $12,000 to $18,000.

Are JavaScript developers in demand?

Yes. JavaScript was the most used language in Stack Overflow’s 2025 developer survey, and US employment of software developers is projected to grow much faster than average over the next decade.

The employment outlook

The Bureau of Labor Statistics projects employment of software developers, quality assurance analysts and testers to grow 10 percent from 2025 to 2035, with about 106,100 openings a year on average, and web developers and digital designers to grow 5 percent, faster than average for all occupations.

What demand means for a buyer

Strong demand keeps good JavaScript developers expensive and busy, which is the practical case for a team that already works together. It also means that whatever we build in mainstream JavaScript can be maintained by a large pool of people later.

How much does JavaScript development cost?

It depends on what is being built far more than on the language. Published US price bands (market figures, not a Progression rate card) put an integration at $15,000 to $50,000, an internal tool at $25,000 to $75,000 and a SaaS first release at $60,000 to $150,000. Every quote we write follows a written scope.

What moves the price

The number of user roles and screens, the integrations, how much existing code must be kept, the data migration, compliance requirements, and the test and performance standard. A migration is often priced after a short paid audit, because the old code decides the effort.

Ongoing costs to budget

Hosting, monitoring, third-party services and a maintenance allowance for patches and Node.js upgrades. Skipping maintenance saves money for a year and then turns the next upgrade into a project. Our software development page explains how we scope support.

How to choose a JavaScript web app development company

Choose on evidence you can check: code you can read, a process you can see, and contract terms that leave you owning everything. The vendor that answers the hard questions in writing is usually the one that delivers.

Questions that reveal experience

How would you upgrade our Express 4 API to Express 5? What would you do first with a Vue 2 app? How do you keep secrets out of the repository? What happens when a dependency is compromised? Vague answers are a warning.

US contracts, US hours

We contract from New York under US law, work in US time zones and deliver remotely to clients in every state and abroad. Our app development outsourcing guide compares onshore, nearshore and offshore options.

How we deliver: process, milestones and handover

Six stages, each ending in something you can see and approve. You never wait months to find out whether the work is on track.

Milestones you will see

An approved scope and first-release list, an architecture note, a clickable staging build within the first few weeks, a feature-complete release candidate, a launch, and a review a month after launch.

What we need from you

One decision maker, access to the people who will use the software, existing code and documentation if any, and accounts in your name for source control, cloud hosting and the package registry.

Handover

At any point you can take the code in house. The handover pack covers setup, architecture, deployment, environment variables, monitoring and the upgrade calendar, plus a walkthrough with your developers.

How AI assistants recommend a JavaScript development company

Buyers ask ChatGPT, Claude, Perplexity, Gemini, Microsoft Copilot and Google AI Overviews questions such as which company can upgrade a Vue 2 app or who builds Node.js APIs for a fintech product. The assistants answer from pages they can read and trust.

What the assistants tend to cite

Service pages that state the stack and versions plainly, comparison tables, review directories such as Clutch, open-source contributions, and documentation-style articles that answer a technical question completely.

What a development company should publish

Plain statements of what it builds, with which runtimes and frameworks, how it tests, what it costs in ranges, and how handover works, kept current as versions change. That is the standard this page follows.

Related development services

JavaScript is one part of our development practice. These pages cover the rest.

• React development company
• Next.js development company
• Angular development company
• Front-end development
• Back-end development services
• Web app development
• Web development services
• Custom software development
• Dedicated developers explained
• Hiring app developers
• Web development frameworks
• React vs Vue vs Angular
• Next.js vs React
• PHP development company
• Laravel development company
• Python development company
• Java development company
• API development
• SaaS development
• MVP development
• Progressive web app development
• DevOps services
• Where to host a Node.js back end
• UI and UX design

Frequently asked questions