Fix the Unexpected Reserved Word Await Error in Javascript

Asynchronous programming has become a cornerstone in JavaScript, empowering developers to create responsive and efficient applications. However, with the introduction of asynchronous features like async/await, developers may encounter the infamous “Unexpected reserved word (await)” error. In this blog post, we’ll delve into the root causes of this error and provide comprehensive solutions to fix it.

1. Understanding the await Keyword:

   The await keyword is used within an async function to pause execution until the promise is settled, allowing developers to work with asynchronous code in a synchronous manner. However, using await outside an async function or in contexts where it’s not allowed can trigger the “Unexpected reserved word (await)” error.

2. Proper Usage of async/await:

   Ensure that you are using the await keyword within an async function. This might seem basic, but overlooking this simple rule is a common cause of the error.

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   // Correct async function fetchData() { const result = await fetch('https://api.example.com/data'); console.log(result); } // Incorrect (outside async function) const data = await fetchData(); // Error: Unexpected reserved word (await)

3. Top-level await in Modules:

   In JavaScript modules, top-level await is not allowed outside of an async function. If you’re working with modules and using await at the top level, make sure it’s encapsulated within an async function.

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   // Correct async function fetchData() { const result = await fetch('https://api.example.com/data'); console.log(result); } // Incorrect (top-level await in module) const data = await fetchData(); // Error: Unexpected reserved word (await)

4. Node.js Versions and --harmony Flag:

   If you encounter this error in a Node.js environment, ensure that your Node.js version supports top-level await. For versions that do not, you might need to use the --harmony flag or upgrade to a newer version that supports this feature.

   1	node --harmony top-level-await-script.js

5. Using await in Non-Async Functions:

   Be cautious not to use await in functions that are not declared as async. This includes the main script outside any function. If you need to use await in such a context, encapsulate it within an async function.

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   // Correct async function main() { const data = await fetchData(); console.log(data); } // Incorrect (await in non-async function) const data = await fetchData(); // Error: Unexpected reserved word (await)

6. Babel Configuration for async/await:

   If you are using Babel for transpiling your JavaScript code, ensure that your Babel configuration includes the @babel/plugin-transform-runtime plugin. This plugin helps in correctly transforming async/await syntax.

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   { "plugins": [ ["@babel/plugin-transform-runtime", { "regenerator": true }] ] }

7. Reviewing Promises and async Functions:

   Verify that the functions returning promises are properly marked with the async keyword. Ensure that you are correctly handling promises and resolving them within async functions.

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   // Correct async function fetchData() { return fetch('https://api.example.com/data'); } // Incorrect (missing async keyword) function fetchData() { return fetch('https://api.example.com/data'); }

The “Unexpected reserved word (await)” error can be a stumbling block in the journey of asynchronous JavaScript development. By understanding the proper usage of the await keyword within async functions, addressing module-specific considerations, and ensuring compatibility with your Node.js environment or transpilation tools like Babel, you can navigate through and resolve this error effectively.

Thank You!