JS: [Deprecation] Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience [duplicate]

Question

I'm receiving the error in my project trying an Ajax request

[Deprecation] Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience.

function getReviews() {
var toReturn = $.ajax({
    url: 'API/reviews.json',
    async: false
}).responseJSON;
return toReturn;
}

I would like to know if there is a different way to write this to not have that error

Answer 1

Synchronous XMLHttpRequest is very bad because they are blocking entire app while it's waiting for a response from the server so you never should be using them.

To make your request asynchronous remove async option and specify callback instead:

function getReviews(cb) {
  $.ajax({
      url: 'API/reviews.json'
  }).done(cb);
}

getReviews(function(data) {
  // Access your data here
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>