Unable to resolve locally installed module

Explanation of the problem

The error message “Unable to resolve module {moduleName} from {place}: {moduleName} could not be found within the project” typically occurs when a locally installed module has not yet been submitted to a repository. This issue can cause the app to break and may require several attempts at troubleshooting to resolve. One solution that has been attempted is to use the command “watchman watch-del-all npm start –reset-cache,” but this did not resolve the issue. Another attempt was to bundle the module with webpack and rollup, but this also did not produce the desired results.

To provide more technical detail, this error occurs in React Native projects when the app is unable to locate a specific module within the project. The error message will provide the name of the module that cannot be found as well as the location within the project where it is expected to be found. In this case, the module in question is a locally installed module that has not yet been submitted to a repository. This can cause confusion for the app as it is unable to locate the necessary files to run properly.

Troubleshooting with the Lightrun Developer Observability Platform

Getting a sense of what’s actually happening inside a live application is a frustrating experience, one that relies mostly on querying and observing whatever logs were written during development.
Lightrun is a Developer Observability Platform, allowing developers to add telemetry to live applications in real-time, on-demand, and right from the IDE.

• Instantly add logs to, set metrics in, and take snapshots of live applications
• Insights delivered straight to your IDE or CLI
• Works where you do: dev, QA, staging, CI/CD, and production

Start for free today

Problem solution for Unable to resolve locally installed module

The “Unable to resolve module {moduleName}from{place}: {moduleName} could not be found within the project” error commonly occurs when attempting to import something from a locally installed module that has not yet been submitted to a repository. The issue can arise when using npm to install the module, which may modify the project’s package.json file in a way that prevents the module from being located during the import process.

One potential solution is to use yarn instead of npm to install the local module. This can be done using the command “yarn add ../”, which will add the module to the project’s dependencies and update the package.json file accordingly. This approach may not work in all cases, however, and additional troubleshooting may be required. It is also important to note that this issue may not be a priority for Facebook, the creator of React Native, and therefore may not have a widely reported solution.

If the issue persists, seeking support from relevant forums or documentation related to the specific development environment may be necessary. This may involve checking for version mismatches or other configuration issues in the project files, or attempting to bundle the module with tools such as webpack or rollup. It is important to try several different solutions before assuming that the issue cannot be resolved. Ultimately, the best solution may depend on the specific circumstances of the project and the development environment being used.

Other popular problems with React

Problem: Virtual DOM performance issues

One of the most common problems with React is related to performance issues with the virtual DOM. The virtual DOM is a mechanism that React uses to update the view in response to changes in the underlying data. When the state of a component changes, React will first update the virtual DOM, and then update the actual DOM. This process can be slow, particularly if the component has a large number of child elements.

Solution:

To solve this problem, developers can use techniques such as shouldComponentUpdate, which allows components to control when they should re-render, or use the React.memo higher-order component, which only re-renders a component when its props change. Additionally, developers can use the React DevTools extension to identify and optimize components that are causing performance bottlenecks.

Problem: Managing state and props

Another common problem with React is related to managing state and props. React components can have both state and props, which are used to store and pass data between components. However, when a large number of components need to share and update data, it can become difficult to manage and maintain the flow of data.

Solution:

To solve this problem, developers can use a centralized state management library such as Redux or MobX. These libraries allow developers to store all of the application’s state in a single place, and provide a mechanism for updating and sharing that state across all components. Additionally, developers can use the useContext and useReducer hooks to manage state within a component tree.

Problem: Handling Forms

React forms can also be a source of pain for developers, as they require a lot of boilerplate code to handle changes and validation. Forms can be tricky to handle because they often involve multiple inputs, which need to be controlled and updated correctly.

Solution:

To solve this problem, developers can use libraries such as Formik and react-hook-form to handle forms in React. These libraries provide simple APIs for controlling form inputs and handling validation. Additionally, developers can use the useState and useEffect hooks to handle form input changes and validation manually.

A brief introduction to React

React is a JavaScript library for building user interfaces. It was developed by Facebook and is now maintained by a community of developers. React allows developers to build reusable UI components, which can be composed to create complex user interfaces. React uses a virtual DOM (Document Object Model) to improve performance by limiting the amount of changes that need to be made to the actual DOM. The virtual DOM is a lightweight representation of the actual DOM and it allows React to compare the current state of the virtual DOM with the previous state, and make only the necessary changes to the actual DOM.

React follows a component-based architecture, where the user interface is broken down into small, self-contained components that can be easily reused and composed to create more complex UI. React components can have both state and props, which are used to store and pass data between components. React also provides a mechanism for handling events, such as user clicks, through the use of event handlers. React also provides a set of lifecycle methods that developers can use to control when a component is created, updated, and destroyed. This allows developers to control the behavior of their components and optimize performance.

Most popular use cases for React

1. Building reusable UI components React allows developers to build reusable UI components that can be composed to create complex user interfaces. Each component is self-contained and can manage its own state and props. This allows developers to easily reuse and maintain their code.
2. Dynamic User Interfaces React uses a virtual DOM to improve performance by limiting the amount of changes that need to be made to the actual DOM. This allows developers to build dynamic user interfaces that can efficiently update in response to changes in the underlying data.
3. Building complex web applications React can be used to build complex web applications that require efficient updating of dynamic data. React also provides a set of lifecycle methods that developers can use to control when a component is created, updated, and destroyed. This allows developers to control the behavior of their components and optimize performance.

class Counter extends React.Component {
  constructor(props) {
    super(props);
    this.state = { count: 0 };
  }

  handleClick = () => {
    this.setState({ count: this.state.count + 1 });
  }

  render() {
    return (
      <div>
        <p>Count: {this.state.count}</p>
        <button onClick={this.handleClick}>
          Increment
        </button>
      </div>
    );
  }
}