Trace current user's location via javascript with CloudFlare provided the /cdn-cgi/trace is enabled.

cloudflare-trace.js

(function($){
  $(function(){
    $.ajax({
      contentType: 'application/text; charset=utf-8',
      crossBrowser: true,
      type: 'GET',
      url: '/cdn-cgi/trace',
    }).done(function(d){
      var data = d.replace(/[\r\n]+/g, '","').replace(/\=+/g, '":"');
          data = '{"' + data.slice(0, data.lastIndexOf('","')) + '"}';
      var jsondata = $.parseJSON(data);
      console.log(jsondata.loc);
    });
  });
})(jQuery);

Convert Return Format to JSON

Updated (September 2022):

async function getCloudflareJSON(){
let data = await fetch('https://1.1.1.1/cdn-cgi/trace').then(res=>res.text())
let arr = data.trim().split('\n').map(e=>e.split('='))
return Object.fromEntries(arr)
}

getCloudflareJSON().then(console.log)

use https://cf-ns.com/cdn-cgi/trace in China

fetch(`https://${location.hostname}/cdn-cgi/trace`)
.then(res => res.text() ).then(t => {
    var data = t.replace(/[\r\n]+/g, '","').replace(/\=+/g, '":"');
        data = '{"' + data.slice(0, data.lastIndexOf('","')) + '"}';
    var jsondata = JSON.parse(data);
    console.log(jsondata);
})

code if page is add to cloudflare

• /cdn-cgi/trace is work on every domain on cloudflare DNS or network