Await has no effect on the type of this expression

The error message “await has no effect on the type of this expression” is usually related to incorrect usage of the await keyword in JavaScript or TypeScript.

The await keyword can only be used inside an asynchronous function, which is a function defined with the async keyword. The purpose of the await keyword is to pause the execution of the function until a given Promise is resolved or rejected, and then resume the execution with the result of the Promise.

Here’s an example to illustrate the correct usage of await:

    
async function fetchData() {
  const response = await fetch('https://api.example.com/data');
  const data = await response.json();
  return data;
}

fetchData()
  .then(data => {
    console.log(data);
  })
  .catch(error => {
    console.error(error);
  });
    
  

In this example, the function fetchData is declared as an asynchronous function using the async keyword. Inside the function, we use the await keyword to wait for the result of the fetch function, which returns a Promise representing the response of an HTTP request. Then, we can use another await to retrieve the JSON data from the response.

Finally, we call the fetchData function and handle the result using the then and catch methods of the Promise. Note that the then and catch methods are not affected by the await keyword, as they are outside the asynchronous function context.

If you encounter the “await has no effect on the type of this expression” error, make sure that:

• The code using await is inside an asynchronous function declared with the async keyword.
• The expression following the await keyword is a Promise or another valid awaitable value. It should not be a regular variable or constant, as that would not provide the expected behavior.