get the Ajax return value

How do I get the Ajax return value?
When submitting, Ajax will go to see the DB and the return value will indicate the error or proceed as it is.
(The code itself is broken in many ways below.)

html    
<form action="NEXTPATH"...>
   <input type="text" id="email">
   <input type="submit" id="submit" value="send">
</form>
<divid="error"></div>

So, in JS,

$(function(){
    $("#submit").click(function(){
        function testajax(){
            return$.ajax({
                type: 'get',
                datatype: 'json',
                url: 'api.php',
            });
        }

        var re=testajax().done(function(data){
            console.log(data['status']);
            if(data['status']=='OK'&data['message']==false){
                return false;
            }
        });

        console.log(re);
        if(re==false){
            $("#error").html('Error.');
        }
        return;
    });
});

Like this, api.php simply returns the value in json format.

{"status":"OK", "message":true}

Ajax itself works well and can take the value of json, but the expected return value from the function testajax() is not returned.
As it is asynchronous, the order of execution does not go as expected, and at this time console.log(re); is running first, returns OBJECT object, and then console.log(data['status']); is running.Also, testajax() will return [Object {readyState:1}] instead of the returned value.
1. Communicate via Ajax and make various decisions based on the returned values.
2. I want to return the value as the return value of the function.
That's all, but it's not going well.

testajax().done(function(data){
....
}

It works fine, but I want to return false (or other values are acceptable), but it doesn't return, so the submit action eventually progresses because it can't control false and true.

Please tell me who knows more.
Thank you for your cooperation.