将回调推迟到setTimeout完成之前

Question

I have searched everywhere for a solution to this but have not been able to find anything thus far (I am probably using the wrong keywords! If this is a duplicate, please point out and I will delete) .

Could one of you brilliant SO geniuses kindly explain to me why the following does not work as one would hope? What I mean by this is the complete callback is called before the setTimeout has completed within the success callback and I don't quite understand why.

$.ajax({
    url: options.url,
    data: options.data,
    success: function(){
        setTimeout(function(){
            console.log('firing');
        },2000);
    },
    dataType: options.dataType,
    complete: function(){
        console.log('ended');   
    }
});

Is it because a new thread has been started by the setTimeout within the success callback?

Is this possible to achieve without passing in a callback function into the success callback?

Answer 1

It happens because setTimeout() does not block the execution of code.

Therefore the complete callback fires at the same moment as it would without your call to setTimeout() .

You will have to put your console.log('ended'); call into a timeout (too) or call your complete handler inside the timeout. :)