Ethereum: Why on printing I get value of null from API call in Loop

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Ethereum: Why “null” Value Erupted in API Call in Loop

As cryptocurrency prices fluctuate rapidly, it can be challenging for developers to work with APIs that provide real-time data. One such API is the Ethereum TradingView API, which offers access to various financial markets, including Bitcoin (BTC) on the USDT pair.

However, when trying to retrieve price data using APIs like getPriceAction and getRSI, a “null” value emerged unexpectedly in some cases. This phenomenon has left developers scratching their heads, wondering why this is happening.

The Issue

The issue at hand lies in how we handle API responses in loops. When you try to iterate over an array (COIN LIST) of crypto coins using for loops or other iteration constructs, each element can be either a value or null. In our case, it seems that the getPriceAction and getRSI functions return null values ​​for some of the API calls.

Breaking Down the Code

To understand why this is happening, let’s break down the code:

const COIN_LIST = [

  'BTCUSDT',

  // ...

];


for (let coin or COIN_LIST) {

  const price = getPriceAction(coin);

  const rsi = getRSI(price);


  console.log(DATA); // This line will print "null" in some cases


  if (!price) {

    // Handle the null value here

  }

}

In this code snippet, we iterate over each element of COIN_LIST and call getPriceAction and getRSI functions to retrieve price data. The console.log(DATA) statement is only executed when a non-null value is retrieved from these functions.

The Solution

To resolve this issue, you can add null checks before logging the data to the console:

const COIN_LIST = [

  'BTCUSDT',

  // ...

];


for (let coin or COIN_LIST) {

  const price = getPriceAction(coin);

  const rsi = getRSI(price);


  if (!price) {

    continuous; // Skip this iteration and move on to the next element

  }


  console.log(DATA); // This line will print the correct data


  if (DATA === null || DATA !== 'null') {

    // Handle unexpected values ​​here

  }

}

By adding these checks, you can prevent the console.log(null) statements from appearing in your logs. Instead, the loop will skip to the next iteration and continue processing the rest of the array.

Additional Tips

To further improve your code’s robustness:

• Use optional chaining

  : To avoid null checks, use optional chaining (?.) instead of direct null checks.

const price = getPriceAction(coin).then((data) => data.price);

• Handle API errors: Don’t forget to handle any potential errors that may occur during API calls, such as network issues or server downtime.

• Consider caching results: If you’re working with large datasets, consider caching the retrieved price and RSI values ​​to prevent unnecessary API calls.

By following these tips, you can write more efficient and reliable code that handles null values ​​in loops without encountering errors.