jQuery development company
jQuery development services for businesses running revenue-critical sites on jQuery: patching outdated versions, fixing plugin conflicts, adding features without breaking old pages, and planning a gradual exit to vanilla JavaScript or a modern framework when it pays off.
- Senior engineers · IST + EST overlap
- NDA on day 1
- 24-hour reply
- Projects shipped
- 50+
- Code ownership
- 100%
- Client rating
- 4.8/5
- First reply
- 24h
A jQuery development company for living codebases
Krapton is a jQuery development company for businesses whose live products still run on jQuery, often through WordPress themes, Bootstrap 3 or 4 builds, legacy admin panels and e-commerce templates. Our engineers maintain and extend that code without forcing a rewrite: they untangle event handlers bound in several places, replace deprecated or removed calls such as .bind, .delegate and .size, and upgrade old releases with the jQuery Migrate plugin logging every incompatible call. Versions before 3.5.0 carry known cross-site scripting issues in HTML parsing, so an upgrade is often a security task as much as a technical one. For new interactive products we rarely recommend jQuery; modern browsers expose querySelector, fetch and classList natively, and React, Vue, Alpine.js or htmx handle state and partial updates more cleanly. Where it makes sense, we plan a gradual migration that rewrites one widget or page at a time, so the site keeps earning while the dependency shrinks.
jQuery development services
jQuery version upgrades
Upgrades from jQuery 1.x or 2.x to a supported jQuery release, using jQuery Migrate in development to log incompatible calls, then removing it once the console is clean.
Security patching and audits
Reviews of jQuery and plugin versions against known CVEs, fixes for unsafe .html() calls fed by user input, and Content Security Policy changes that block injected scripts.
Plugin repair and replacement
Debugging broken sliders, date pickers and form validators, resolving duplicate jQuery copies loaded by different scripts, and replacing abandoned plugins with maintained, dependency-free alternatives.
Feature work on legacy pages
New AJAX forms, filters and interactive widgets added to existing jQuery pages using delegated events with .on() and promise-based requests, written to match the site’s current conventions.
Migration to vanilla JavaScript
Rewriting jQuery modules into modern JavaScript with querySelectorAll, fetch, classList and addEventListener, bundled by Vite or esbuild, so the library can eventually be removed entirely.
Framework migration planning
Incremental moves from jQuery to React, Vue or htmx, mounting new components inside existing pages and retiring jQuery widgets one route at a time instead of freezing the product.
Why teams choose Krapton for jQuery
Senior engineers, fixed scope, and code you own — the things agencies promise and rarely deliver.
No rewrite-first agenda
We recommend replacing jQuery only where it causes cost, risk or slowness; stable code that works and is patched can stay, and we say so plainly.
Characterization tests first
Before touching fragile scripts, we record current behavior with Playwright tests, so upgrades and refactors are checked against what users actually do on the page.
Security treated as scope
Every engagement includes a dependency check for jQuery, jQuery UI and plugins, with findings ranked by exposure rather than buried in a long report.
Readable code left behind
Anonymous callbacks nested several levels deep are split into named modules with clear selectors and comments, so the next developer can change one widget without fear.
How a jQuery project runs with Krapton
01
Dependency and risk audit
We list jQuery, jQuery UI and plugin versions, map which pages use them, and rank known vulnerabilities and breakages by business impact.
02
Behavior capture
Key user flows such as checkout, search filters and forms are recorded as Playwright tests so later changes are measured against today’s behavior.
03
Fix, upgrade or replace
Each module gets one decision: patch it, upgrade it under jQuery Migrate, or rewrite it in vanilla JavaScript, agreed with you before work starts.
04
Release and monitor
Changes ship in small releases with browser error tracking in Sentry, so any regression on older pages or browsers shows up quickly and is rolled back.
The jQuery stack we build with
jQuery development: questions answered
What does a jQuery development company work on today?
Mostly it keeps existing jQuery code safe, working and changeable. Typical work includes upgrading old jQuery versions, fixing plugin conflicts, adding AJAX features to legacy pages, tightening security around DOM insertion, and planning a gradual move to vanilla JavaScript or a framework. Krapton treats jQuery as a maintenance and migration skill rather than a reason to start new single-page apps with it.
Should we remove jQuery from our website?
Remove it only when there is a clear payoff. Good reasons include an outdated version with known vulnerabilities that cannot be upgraded, page weight on mobile-critical routes, or a planned move to React or Vue that makes two DOM models awkward. If the code is upgraded, patched and rarely changed, keeping jQuery is often the sensible, lower-risk decision, and that advice is part of our audit.
Is an old jQuery version a security risk?
Yes, versions before 3.5.0 have published cross-site scripting flaws in how HTML strings are parsed, and versions before 3.4.0 allow prototype pollution through $.extend. Old plugins can be worse than the core library. We upgrade jQuery, update or replace vulnerable plugins, stop passing untrusted input to .html() or $(), and add a Content Security Policy as a second layer of defense.
How do you migrate from jQuery to React or vanilla JavaScript without a big-bang rewrite?
We migrate one widget or route at a time while both approaches coexist. Simple behaviors such as toggles, AJAX forms and tabs move to vanilla JavaScript modules; stateful screens move to React or Vue components mounted into existing markup. The rule during the transition is that one part of the DOM belongs to one owner, which avoids jQuery and React fighting over the same elements.
How is the cost of jQuery development services estimated?
It is estimated from the size and condition of the existing code, not from a fixed menu. The main drivers are how many pages and plugins are involved, the jQuery version gap, whether automated tests exist, browser support requirements, security findings that must be fixed first, and whether the goal is maintenance, an upgrade or a full migration. An audit turns those into a written, scoped estimate.
Ready to build? Tell us what you have in mind.
Send a short brief and a senior engineer will reply within one business day with next steps — no sales fluff.