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Solving the imgSrc Undefined Error in React

Learn how to fix the common `imgSrc` is not defined error in React with this step-by-step guide that explores state management and useEffect. --- This video is based on the question https://stackoverflow.com/q/71004751/ asked by the user 'kawnah' ( https://stackoverflow.com/u/5481714/ ) and on the answer https://stackoverflow.com/a/71004796/ provided by the user 'fullstack' ( https://stackoverflow.com/u/12425363/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: 'imgSrc' is not defined no-undef Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- Unlocking the Mystery Behind 'imgSrc is Not Defined' Error in React When working with React, developers often encounter JavaScript errors that stem from scope and state management issues. One common error that many face is the imgSrc is not defined warning when attempting to render images from an API. If you’ve found yourself grappling with this issue, you’re not alone. This guide will delve into the problem and provide an easy-to-understand solution. Understanding the Problem The crux of the problem lies in how JavaScript handles variable scope. Variables declared inside a block (like within a function or useEffect hook) have local scope, meaning they’re not accessible outside that specific block. This is why when you try to use imgSrc outside the axios call inside your useEffect hook, the variable is considered "undefined." In addition, React has its own rules regarding rendering. When you want to change the display based on the value of a variable, you must use the setState function. Relying on a standard variable won't trigger a re-render, and thus the image will not display as intended. The Solution: Using State in React To resolve the issue and successfully render images fetched from an API, you will need to utilize React's useState hook effectively. Let’s break this down step-by-step: Step 1: Setting Up State Start by importing the useState hook from React and declare your state variables at the beginning of your component. Here’s how you can structure your state management: [[See Video to Reveal this Text or Code Snippet]] Step 2: Making the API Call with useEffect Inside the useEffect hook, you’ll want to fetch the image URL using axios. Once you receive the data, update the state variable with setImgSrc, which will also trigger a re-render of your component: [[See Video to Reveal this Text or Code Snippet]] Step 3: Rendering the Image With imgSrc now stored in state, you can use it in your return statement. React will re-render the component whenever imgSrc changes, meaning the image will appear once it's successfully fetched: [[See Video to Reveal this Text or Code Snippet]] Putting It All Together Here’s a full example of how your component should look after making these changes: [[See Video to Reveal this Text or Code Snippet]] Conclusion By shifting your approach from local variable management to using React's state management with useState, you'll effectively solve the imgSrc is not defined issue. This not only lets you fetch and display images from an API seamlessly but also keeps React informed of when to re-render your components. Happy coding!