如何从外部URL获取JSON数据

Question

I would like to be able to read information from a small page.

I have the address of a JSON service that displays the following information:

And I wish I could keep the number that appears.

I tested this example and work correctly, however when I try with my URL nothing happens. I do not know if I am to understand the problem correctly, but I wish someone could please help me.

If have any questions, I try to explain as best as possible.

I ask now apologize for the inconvenience.

The code that I used

var getJSON = function(url) {
  return new Promise(function(resolve, reject) {
    var xhr = new XMLHttpRequest();
    xhr.open('get', url, true);
    xhr.responseType = 'json';
    xhr.onload = function() {
      var status = xhr.status;
      if (status == 200) {
        resolve(xhr.response);
      } else {
        reject(status);
      }
    };
    xhr.send();
  });
};

getJSON('http://MYADDRESS/json.do?_ULN[1]').then(function(data) {
    alert('Your Json result is:  ' + data.result); //you can comment this, i used it to debug

    result.innerText = data.result; //display the result in an HTML element
}, function(status) { //error detection....
  alert('Something went wrong.');
});

Answer 1

You can't for security reasons. See the same origin policy for JavaScript.

There are some workarounds that exploit browser bugs or corner cases, but using them is not recommended.

The best approach is having a server-side proxy that receives Ajax requests, and in turn, sends HTTP requests to other servers. This should be carefully implemented by sanitizing input and whitelisting the types of requests that are sent, and the servers that are contacted.

Answer 2

Your problem exist because of the browser Same-origin policy.

One solution to your problem is to use the method JSON-P or CORS. The method is well explained here : http://json-p.org/ and here : http://www.sitepoint.com/jsonp-examples/ .