If I am correct, "A" in "AJAX" means sending a HTTP request asynchronously without waiting for a HTTP response.

I learn that we can send an asynchronous HTTP request by XMLHttpRequest, for example:

function handleButtonPress(e) { 
    var httpRequest = new XMLHttpRequest(); 
    httpRequest.onreadystatechange = handleResponse; 
    httpRequest.open("GET", e.target.innerHTML +  ".html"); 
    httpRequest.send(); 
} 

How can we send a HTTP request synchronously?

If I am correct, "A" in "AJAX" means sending a HTTP request asynchronously without waiting for a HTTP response.

I learn that we can send an asynchronous HTTP request by XMLHttpRequest, for example:

function handleButtonPress(e) { 
    var httpRequest = new XMLHttpRequest(); 
    httpRequest.onreadystatechange = handleResponse; 
    httpRequest.open("GET", e.target.innerHTML +  ".html"); 
    httpRequest.send(); 
} 

How can we send a HTTP request synchronously?

• javascript
• xmlhttprequest

• What use case do you have for synchronous requests? In general they are not remended (certain browsers even state this in their console when a synchronous request is sent) – NielsNet Commented May 3, 2019 at 10:42
• Just put false as the 3rd parameter to open, but a big warning, if you use this feature not inside a WebWorker it might stop working in the future. – Keith Commented May 3, 2019 at 10:42
• I suppose the question is more about alternatives to XMLHttpRequest, no? – raina77ow Commented May 3, 2019 at 10:43
• Possible duplicate of JavaScript console.log causes error: "Synchronous XMLHttpRequest on the main thread is deprecated..." – Jorge Fuentes González Commented May 3, 2019 at 10:46
• @Keith Thanks. where do you remend to look up the API usages? – Tim Commented May 3, 2019 at 11:18

1 Answer 1

The third param in open function is for async request sending. You can set it to false for a synchronous request

function handleButtonPress(e) { 
    var httpRequest = new XMLHttpRequest(); 
    httpRequest.onreadystatechange = handleResponse; 
    httpRequest.open("GET", e.target.innerHTML +  ".html", false); 
    httpRequest.send(); 
}