The End of UMD Builds in Redux v5.0.0: Alternatives and Solutions

Anton Ioffe - January 10th 2024 - 10 minutes read

As Redux vaults into its version 5.0.0, the paradigm shift away from Universal Module Definition (UMD) builds marks a significant milestone in the evolving landscape of JavaScript state management. This evolution not only echoes the industry's stride towards modern standards but also heralds a transformative epoch that seasoned developers must adeptly navigate. Through the unfurling of this discourse, we will dissect the impetus for Redux's pivotal change, illuminate the pathway to embracing ECMAScript Modules, and conquer the build and packaging odyssey that ensues. Moreover, we will arm you with robust refactoring strategies to ensure compliance with the latest Redux best practices and explore the horizons of what these foundational changes portend for the future of state management. Prepare to delve into a realm where agility meets intellect, ensuring that your development prowess remains in lockstep with the cutting edge of web evolution.

Universal Module Definition (UMD) builds have traditionally been a part of the Redux ecosystem, offering a versatile format that supports both CommonJS and AMD as module loaders, as well as providing the ability to be directly included in a browser environment. It’s been an inclusive solution, catering to a diverse range of project configurations to ensure broad compatibility. However, as the tooling and standards of modern web development evolved, the Redux maintainers have recognized a shift in the landscape—most contemporary applications now predominantly use ECMAScript modules (ESM) and CommonJS (CJS).

The Redux team's decision to phase out UMD builds in version 5.0.0 was driven by several compelling reasons. Predominantly, the modern JavaScript ecosystem has moved towards ESM, with an increasing number of environments and tools being designed to natively work with ESM and CJS formats. By focusing on these, Redux aligns with the current and future direction of JavaScript development. This move also aids in simplifying the library's maintenance by removing the necessity to cater to outdated module systems, a process that can be error-prone and time-consuming.

For developers who have been utilizing UMD builds in their applications, the transition brings forth a period of adaptation. The absence of UMD means that if developers previously delivered Redux as a standalone script in the browser, or relied on platforms that explicitly require UMD format, they will need to reconsider their integration approach. It is important to note, though, that Redux v5.0.0 does include a browser-ready ESM build, which can serve as a replacement for those previously using UMD builds via script tags, offering a potential pathway to move forward.

This modification in Redux's build artifacts may prompt developers to re-examine how they bundle their applications. Modern bundlers like webpack and Rollup are designed to work efficiently with ESM, giving rise to a refined development process where optimization can be more fine-grained. As such, developers will be incentivized to update their workflows, resulting in more efficient bundling and a net positive impact on application performance. However, the road to these benefits involves a conscious effort to migrate from deprecated patterns.

Ultimately, this transition underscores the need for developers to maintain an agile approach towards evolving with the JavaScript ecosystem. While the removal of UMD builds necessitates change, it ignites a crucial conversation about adaptation and forward-thinking, encouraging the cultivation of codebases that remain robust through change. Developers tasked with updating existing Redux-dependent applications will need to assess the scope of adaptation required and strategically plan for a smooth transition that complements their application’s architectural demands.

Embracing ECMAScript Modules in Redux

Redux’s commitment to modern web development is illustrated by its embrace of ECMAScript Modules (ESM), which serves as a significant enhancement over the older Universal Module Definition (UMD) builds. The update in Redux v5.0.0 leverages ESM's treeshaking potential, a technique that allows build tools to remove unused code. Subsequently, applications benefit from reduced bundle sizes, leading to faster loading times, especially critical for mobile or bandwidth-constrained users.

The static nature of ESM facilitates advanced static analysis by tools like webpack and Rollup. These tools can now eliminate unreachable code paths more effectively, which can shrink the codebase considerably. This has a direct impact on reducing the memory footprint as the JavaScript engine needs to parse and execute less code, leading to better runtime performance. When unnecessary code is pruned, developers gain not only in terms of performance but also in the modular organization of their code, easing maintenance and promoting better development patterns.

With the release of Redux v5.0.0, developers must ensure their build processes are in sync with ESM-centric outputs to fully capitalize on these efficiencies. Configuration is key as legacy or misconfigured systems could negate the benefits. The toolchain compatibility extends these improvements in performance and lowers memory overhead by making the code leaner thus reducing the amount to load and retain during execution.

Redux’s enhancements continue with the addition of an exports field in package.json. This update articulates clear entry points for module resolutions, tailoring bundle artifacts to their execution environments. Such precision in module delivery cuts down unnecessary overhead by leveraging the most optimized and environment-specific artifacts, aligning with the modern standards of web development.

Transitioning legacy Redux codebases to make use of ESM is more of an inevitable shift than a choice—the benefits it brings are indisputable. Although there may be an initial increase in complexity during the migration, the fundamental improvements to bundling, performance, and memory consumption underscore the necessity of adopting ESM. Ultimately, Redux v5.0.0’s stride towards a modern module system embodies the constant evolution of the JavaScript ecosystem, urging developers to adapt and thrive as web technologies advance.

Overcoming Build and Packaging Challenges

As Redux v5.0.0 has prioritized ESM over other module formats, developers must now ensure that their build tools are configured correctly to handle ESM. This can be a challenge particularly for those who are used to CommonJS and might not have Webpack or Babel set up to work with the new format. It's essential to modify Webpack's configuration to include the module.rules property with an appropriate loader, like babel-loader, which will transpile ESM syntax for browsers that do not yet support it. For Babel, the inclusion of the @babel/preset-env will enable the necessary transformations to ensure compatibility.

// Inside webpack.config.js
module.exports = {
    module: {
        rules: [
                test: /\.js$/,
                exclude: /node_modules/,
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: ['@babel/preset-env']

Further adjustments will be required to optimize the build. Webpack's optimization property can be leveraged to enhance tree-shaking, which is now more effective due to Redux's improved module format. Setting Webpack's usedExports and sideEffects flags helps in discarding unused code, thereby streamlining the bundle size even more.

// Inside webpack.config.js
module.exports = {
    optimization: {
        usedExports: true,
        sideEffects: false

Apart from the build tool configuration, another challenge is to adopt the new features of ES2020 that Redux v5.0.0 outputs in its modern build. This requires ensuring that the environment supports new syntax such as optional chaining and object spread. If the target runtime environments do not support these features, developers will have to rely on Babel further to transpile the code.

// .babelrc or babel.config.js
    "presets": [
                "targets": "> 0.25%, not dead"
    "plugins": ["@babel/plugin-proposal-optional-chaining", "@babel/plugin-proposal-object-rest-spread"]

Developers may also need to refactor their code as Redux v5.0.0 deprecates certain features like createStore. This requires not only a keen understanding of the newer alternatives like configureStore but also how to employ them effectively in the current application architecture.

import { configureStore } from '@reduxjs/toolkit';

const store = configureStore({ reducer: rootReducer });

Finally, performance benchmarks become essential tasks to measure the impact of these changes on application load time and responsiveness. A precise adjustment to the build tools and careful code refactoring are key strategies in overcoming the initial increase in complexity, ensuring seamless adaptation to the Redux v5.0.0 updates, and keeping the application's performance optimized for the end user's benefit. Quantitative data from benchmarks will guide further tweaks, solidifying a developer’s approach toward a more performant and future-ready application architecture.

Refactoring Strategies for Redux v5.0.0 Compliance

Refactoring your Redux codebase to ensure compliance with the version 5.0.0 changes primarily involves transitioning from the createStore function to configureStore. The configureStore function, part of the Redux Toolkit, represents a more opinionated setup that aims to simplify the store setup process. To do this, one must carefully replace the createStore code while ensuring all middlewares and enhancers are appropriately incorporated through the new method. The configureStore automates much of the process, including the setup of the Redux DevTools and the inclusion of thunk middleware by default.

import { configureStore } from '@reduxjs/toolkit';
// Assume rootReducer has been created from combineReducers or similar
const store = configureStore({
  reducer: rootReducer,
  // Additional middleware can be passed here
  middleware: (getDefaultMiddleware) => getDefaultMiddleware().concat(myMiddleware),
  // If needed, DevTools options can be customized here
  devTools: process.env.NODE_ENV !== 'production',

Adapting to strict typing of actions is another crucial aspect of Redux v5.0.0 compliance. With the deprecation of AnyAction and the adoption of UnknownAction, defining each action's type becomes necessary. To accomplish this, you will need to revise your action creators, ensuring each dispatch is accompanied by a trusty action defined with a string literal, ensuring reducer cases are correctly typed and correlated with respective actions.

const ADD_TODO = 'ADD_TODO';
// Action creator with explicit type
function addTodoWithExplicitType(text) {
  return {
    type: ADD_TODO,
    payload: text
// Reducer handling explicit action types
function todosReducer(state = [], action) {
  switch (action.type) {
    case ADD_TODO:
      return [...state, action.payload];
    // ...other actions

Restructuring reducers to conform to new patterns involves ensuring action types are well-defined and reducers are cleanly partitioned to handle specific segments of your state. With this version, reducers must be more predictable and manageable. Leveraging utility functions like createReducer or createSlice from Redux Toolkit can greatly assist in this endeavor.

import { createSlice } from '@reduxjs/toolkit';
// Using createSlice to encapsulate actions and reducers
const todosSlice = createSlice({
  name: 'todos',
  initialState: [],
  reducers: {
    addTodo: (state, action) => {
    // ...other reducers

Additionally, it is highly recommended to conduct a pre- and post-refactoring performance assessment. Monitoring bundle size, memory usage, and execution time will help you gauge the impact Redux v5.0.0 has on your application. Making iterative adjustments and employing performance benchmarks as a feedback loop can fine-tune both user experience and application efficiency.

Enhancing the maintainability of your Redux codebase encompasses embracing stricter type checking. The use of TypeScript or PropTypes to enforce type contracts for actions and state shapes significantly reduces the likelihood of bugs. Also, consider abstracting repeated logic into reusable functions or middleware, which can further batten down your application's state management. Ensuring a robust and easily navigable Redux implementation warrants a dedication to disciplined refactoring in alignment with the emerging norms and best practices Redux v5.0.0 establishes.

Anticipating Future Redux Ecosystem Developments

With Redux v5.0.0 heralding a new era of state management, developers are urged to look beyond the current landscape and envisage the future trajectories of Redux's growth. The revisions instilled in Redux v5.0.0 serve as a springboard for more substantial enhancements down the line, suggesting a deeper trend towards a modular, efficient, and type-safe ecosystem. The emphasis on structured action types and reducers presages a likely consolidation of practices that could streamline state management, making it imperative for developers to habituate themselves with advanced type systems and pattern matching in Redux.

The focus on performance in Redux v5.0.0 also insinuates that further advancements may prioritize runtime efficiency and the minimization of resource consumption. Developers should consider how to exploit intelligent code-splitting and the latest state persistence techniques to keep applications quick and light. Anticipating these trends and incorporating performance-centered design principles now will position web applications favorably for subsequent iterations of Redux and state management patterns more broadly.

Moreover, the lean towards a more type-safe and disciplined Redux suggests a future where integration with languages like TypeScript might become more seamless or perhaps even a standard. As it stands, an anticipation of a tighter synergy between JavaScript and TypeScript could inspire developers to start writing more defensively typed code. Such an approach to coding not only enhances code maintainability but also prepares the team for a smoother transition to more robust type integrations in Redux's updates.

One could also infer that Redux, by streamlining its approach with Redux v5.0.0, is setting the ground for better integration with React's concurrent features or other reactive paradigms. Developers ought to maintain a tight pulse on the evolution within the React ecosystem and consider how asynchronous patterns and state management might intersect more deeply. Embracing a mindset that is reactive to these potential changes will necessitate staying attuned to updates, RFCs, and community discussions surrounding the future of state management.

Lastly, developers should ask themselves how Redux's trajectory will influence their tooling and workflow. It is prudent to presume continuous improvement in toolchains, potentially impacting debugging, testing, and state monitoring utilities. How will the developer experience evolve, and what can be done now to refine the workflow in anticipation of these developments? Incrementally adopting the best practices proposed by Redux v5.0.0, such as taking advantage of configureStore, is a proactive measure in ensuring that applications remain adaptable to the ongoing march of Redux's innovations.


The article explores the transition from Universal Module Definition (UMD) builds to ECMAScript Modules (ESM) in Redux v5.0.0. It highlights the benefits of embracing ESM, such as reduced bundle sizes and improved runtime performance, and provides guidance on overcoming build and packaging challenges. The article emphasizes the importance of refactoring strategies to ensure compliance with Redux v5.0.0, including transitioning to the configureStore function and adopting stricter type checking. It also encourages developers to anticipate future developments in the Redux ecosystem and consider how they can optimize their code and workflows accordingly. The challenging technical task for readers involves modifying their build tools and updating their code to align with Redux v5.0.0, while also considering potential future trends in state management and web development.

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