Ajax Cross-domain access to error 501 resolution _AJAX related

question: Ajax cross-domain access error 501

Run the following code to make an error 501

$.ajax ({
      type: "POST",
    URL: "http://192.168.1.202/sensordata.php",

    contentType: ' Application/json; Charset=utf-8 ',
    data:JSON.stringify (ajaxpostdata),
    dataType: ' JSON ',
    success:function (data) {
      / /on Ajax success do this
      console.info ("success.");
      if (data["status" = = = "OK") {
        alert ("The Settings is OK.") The Machine is rebooting. ");
      }
    ,
    error:function (XHR, ajaxoptions, thrownerror) {
      //on error do This
      console.info ("error.");
      if (Xhr.status =) {

        alert (ajaxoptions);
      }
      else {
        alert (xhr.status);
        alert (thrownerror);
      }
    }
  );

Workaround:

Remove contentType: ' Application/json; Charset=utf-8 '

Reason:

1 in the Cross-domain, in addition to ContentType for application/x-www-form-urlencoded, Multipart/form-data or text/plain outside, Triggers a request that the browser first sends the method to options.

2 For example, your original request was a method method post, and if the Allow attribute in the header returned by the first request does not have a post method,

3 So the second request is not sent, the browser console will be an error, telling you that the POST method is not supported by the server.

Reference Document: http://www.foreverpx.cn/2016/06/22/cross_content_type/

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