jQuery.ajax() sends request more than once if headers object is set

Question

When I run this, it sends two requests for some reason. When I remove the headers object though it only runs once. Why is it running twice with the headers object?

$.ajax({
    type: "get",
    headers: {
        Time: time
    },
    url: getHost() + "/leaderboard/top?gameId=" + gameId + "&token=" + createToken([gameId, time]),
    dataType: "json",
    complete: function(data){
        showOutput(JSON.parse(data.responseText));
    }
});

When I look in the chrome network inspector, I see that under Method one says GET and the other says OPTIONS. Other than that the request is exactly the same.

On the server I have the following headers set:

this.res.setHeader("Content-Type", "text/json; charset=utf-8");
this.res.setHeader("Access-Control-Allow-Origin", "*");
this.res.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Time");

This may help you: http://stackoverflow.com/questions/5544422/jquery-ajax-executed-twice — freethinker, May 14 '15 at 17:28
BTW, you can trigger a non-preflighted request with Content-Type of `text/plain` and not `text/json`. — Kariem Muhammed, May 14 '15 at 17:34
check this https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS#Preflighted_requests — Kariem Muhammed, May 14 '15 at 17:36

Musa · Accepted Answer · 2015-05-14T17:35:13.127

1

Under certain conditions(in this case the presents of the time header) for cross origin GET request a pre-flight OPTIONS request is sent first to make sure that the receiving server accepts these kinds of requests.

Do some reading on Cross Origin Resource Sharing and Same Origin Policy.

edited May 14 '15 at 17:35

answered May 14 '15 at 17:30

Musa

96,336
17
118
137

I have updated the question with the server headers that I am using. Are those headers what you are talking about? – Get Off My Lawn May 14 '15 at 17:33
@TheBoogieMan no the headers set in ajax request. – Musa May 14 '15 at 17:37

jQuery.ajax() sends request more than once if headers object is set

1 Answers1