How to synchronously retrieve website in JS?

I have a synchronous function myFunction in which I need to retrieve the contents of a website. However, the async parameter I’m currently using is deprecated and I’m only aware of async AJAX requests. Thus I’m looking for a better solution how I can wait for the asynchronous call to finish and process the result synchronously.

The myFunction function is embedded in a library that I cannot modify. Thus there are the following limitations:

• I cannot turn myFunction into a async function
• I cannot use any third-party libraries, only plain javascript and jQuery

    var myFunction = function(url) {
        var mydata = false;

        $.get(
            {
                url: url,
                async: false
            })
            .done(content => {
                // Do something with content.

                if(content === 'xyz') {
                     mydata = content;
                     return;
                }
            });

        return mydata;
    };

I have already looked into Promises and async/await but I couldn’t find a good solution for wrapping async calls. I also didn’t found another method that can make synchronous Get requests. What’s the best way to implement this?