What is the best way to handle multiple calls to `response.json()` in Playwright's `waitForResponse` function?

Answer

Working with response.json() in Playwright

In Playwright, response.json() is a method that extracts the JSON body from a response object. It's not destructive and can be called multiple times without any issues. Each time you call it, it parses the response body again and returns a new promise with the parsed JSON data.

Here are a couple of best practices to follow when using response.json():

Store the Result in a Variable

To avoid making multiple calls to response.json(), store its result in a variable and reuse it. This improves performance. Here's how you can do it:

const jsonResponse = await response.json();
// Now, you can use jsonResponse wherever needed

Handle Errors Gracefully

When working with asynchronous operations like parsing JSON, it's crucial to handle errors properly. Use try-catch blocks or .catch() methods on promises. This ensures that if an error occurs during parsing, your code doesn't break and allows for appropriate error handling.

try {
  const jsonResponse = await response.json();
  // Use jsonResponse wherever needed
} catch (error) {
  // Handle error gracefully
}

By following these practices, you can safely use response.json() multiple times without encountering any issues or unexpected behavior when using Playwright's waitForResponse function. For more tips on efficient Playwright test scripts, check out this blog post.