In JavaScript, when you use XMLHttpRequest, you cannot directly make it synchronous when the async option is set to true. The async option in XMLHttpRequest determines whether the request is executed asynchronously or synchronously. When async is set to true (the default value), the request is asynchronous, and the code continues executing without waiting for the response. On the other hand, when async is set to false, the request becomes synchronous, and the code execution waits for the response before continuing.

In modern JavaScript, it is generally recommended to use asynchronous code and handle responses using promises, callbacks, or async/await functions. Synchronous requests can cause the UI to freeze, leading to a poor user experience. That's why the synchronous option is deprecated in modern browsers, and it is best to avoid using it.

If you still want to make the XMLHttpRequest synchronous when async is set to true, you can use async/await or callbacks to simulate synchronous behavior. Here's an example of how you can use async/await:

javascript
async function makeAsyncRequest(url) { return new Promise((resolve, reject) => { const xhr = new XMLHttpRequest(); xhr.open('GET', url, true); // true for asynchronous (default) xhr.onload = () => { if (xhr.status === 200) { resolve(xhr.responseText); } else { reject(new Error('Request failed')); } }; xhr.onerror = () => { reject(new Error('Network error')); }; xhr.send(); }); } async function main() { try { const response = await makeAsyncRequest('https://example.com/data'); console.log(response); // Handle the response here } catch (error) { console.error(error); } } main();

By using async/await, the code appears synchronous, but the actual XMLHttpRequest is still asynchronous, making it a non-blocking operation.

Again, it's essential to use asynchronous patterns for better performance and user experience. Only use synchronous requests if you have a specific reason to do so and understand the potential consequences.

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