ReferenceError when making async API request - function not initialized

[Hermione_Book]

I’m facing an issue with an async function that attempts to reach an external API. Each time I execute my script, I encounter this error:

Uncaught (in promise) ReferenceError: Cannot access 'fetchApiData' before initialization

Here’s the snippet of my code:

const API_TOKEN = import.meta.env.VITE_API_TOKEN;
const LOCATION_API_URL = "https://location-service.p.rapidapi.com/lookup?output=json";
const API_HOST = "location-service.p.rapidapi.com";

const fetchApiData = async(endpoint, hostname) => {
  const result = await fetch(endpoint, {
    method: "GET",
    headers: {
      "content-type": "application/json",
      "x-rapidapi-host": hostname,
      "x-rapidapi-key": API_TOKEN
    }
  })

  if (!result.ok) {
    throw new Error(`Request failed with status: ${result.status}`)
  }

  return await result.json();
}

const executeRequest = async() => {
  // RETRIEVE LOCATION DATA
  const fetchApiData = await fetchApiData(LOCATION_API_URL, API_HOST);
  console.log(fetchApiData);
}

executeRequest();

I’m struggling to understand why I’m encountering this initialization error. The function appears to be defined correctly before it gets called. What could be the issue here?

[SparklingGem]

yeah, I see what’s happening! you’re overwriting your function name with a const variable in executeRequest. that’s why javascript throws the reference error - it thinks fetchApiData doesn’t exist when you try to call it. just use a different variable name like const response = await fetchApiData(...) and you’re all set.

[mythicMuse]

Yeah, everyone’s right about the naming collision - you’re shadowing your function with that const variable.

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Now I just automate the whole thing. Latenode lets you build API workflows visually - no async functions needed. Connect endpoints, set headers and tokens, handle responses through a visual interface. No naming conflicts or promise debugging.

We’ve moved most of our team’s integrations this way. Less code, zero async errors to fix.

Latenode - Create AI Agents & Autonomous Workflows | No-Code &...

[opalEcho]

The Problem:

You are encountering a ReferenceError: Cannot access 'fetchApiData' before initialization error in your JavaScript code. This error occurs because you are unintentionally shadowing the fetchApiData function with a variable of the same name within your executeRequest function. The code thinks you’re trying to use a variable named fetchApiData before it’s been assigned a value, while actually you’re trying to call the async function.

TL;DR: The Quick Fix:

Rename the variable inside executeRequest to avoid the naming conflict. Change this line:

const fetchApiData = await fetchApiData(LOCATION_API_URL, API_HOST);

to this:

const locationData = await fetchApiData(LOCATION_API_URL, API_HOST);

Now, locationData will store the result of your API call, and the function fetchApiData remains accessible and correctly called. Also, remember to use locationData instead of fetchApiData in any subsequent code that needs the data.

Understanding the “Why” (The Root Cause):

JavaScript’s variable scoping and hoisting can sometimes lead to unexpected behavior, particularly when dealing with asynchronous functions and variable naming. In your original code, you defined the fetchApiData function. However, within the executeRequest function, you declared a const variable also named fetchApiData. JavaScript, during the parsing phase, doesn’t fully understand the asynchronous nature of the await keyword. It sees a variable declaration with the same name as the function before the actual function call and assumes that you are trying to use the variable before it’s been assigned a value, leading to the error. By using a distinct name for the variable that stores the result of the API call, you remove the ambiguity and prevent the naming conflict.

Step-by-Step Guide:

1. Identify the Naming Conflict: Locate the executeRequest function in your code. Observe the line where you attempt to assign the result of the fetchApiData function call to a variable with the same name.

2. Rename the Variable: Change the variable name from fetchApiData to something descriptive and unique, such as locationData or apiResponse. The corrected line will look like this:

   const locationData = await fetchApiData(LOCATION_API_URL, API_HOST);
   

3. Update Subsequent Code: Make sure to replace all occurrences of fetchApiData (the variable, not the function) in the executeRequest function with the new variable name (locationData). For example, if you were to log the fetchApiData variable, change console.log(fetchApiData); to console.log(locationData);.

4. Retest Your Code: Run your JavaScript code again. The ReferenceError should be resolved, and your API call should now execute correctly.

Common Pitfalls & What to Check Next:

• Similar Variable Names: Be extra cautious when naming variables and functions, especially in asynchronous operations. Avoid using names that are very similar to existing functions or variables to prevent accidental shadowing.
• Debugging Asynchronous Code: When debugging asynchronous code, utilize console.log statements strategically to trace the execution flow and variable values at various stages of your API call.
• Async/Await Best Practices: Familiarize yourself with the best practices of using async/await in JavaScript, paying special attention to variable scope and function naming conventions.

Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!

[lucasg]

You’ve got a variable shadowing problem. You’re declaring const fetchApiData = await fetchApiData(...) - basically trying to use the function name for your variable too. JavaScript thinks you’re using the variable before it exists, which throws that initialization error.

I’ve made this exact mistake tons of times with async functions. The hoisting gets weird when function names clash with const variables.

Just rename your result variable to something like apiResponse or locationData. Problem solved - no more naming collision and your async call works fine.

These naming conflicts are super annoying to debug since everything looks right at first.

[olivias]

The issue you’re encountering is due to a name conflict in your executeRequest function. When you declare const fetchApiData = await fetchApiData(...), you’re unintentionally masking the function with a variable of the same name, which results in a reference error. To resolve this, simply change the result variable name to avoid confusion. Your modified function should look like this:

const executeRequest = async() => {
  const locationData = await fetchApiData(LOCATION_API_URL, API_HOST);
  console.log(locationData);
}

Using a different name for the variable will allow you to call the function correctly.