Is it possible to use javascript to download JSON object from another domain/server?

Question

那段代码会是什么样的？

Answer 1

That other domain/server needs to support JSONP, which basically wraps the JSON in a callback.

In jQuery, the call would look like this:

$.getJSON(
     'http://otherdomain.com/api/whatever?callback=?', 
     { key: 'value', otherkey: true },
     function(data){
        //handle response
     }
);

The actual response from the other server (if you looked at what was actually being sent) would look like this:

// With this url:
http://domain.com/api/method?callback=the_callback_function_name

// The response would look like this:
the_callback_function_name({ "json": "data here"});

The jQuery getJSON method automatically handles JSONP when you supply the extra callback=? . Just keep in mind some sites using different names like json_callback=? . The important part is that you include it as part of the URL and don't try to add callback: '?' to the data part of the getJSON function.

Answer 2

Only via JSONP. Whether you use jQuery or some other framework, it boils down to a script block like this:

<script type="text/javascript" src="http://path.to/your/javascript"></script>

The <script> block is immune from cross-domain restrictions. The caveat is that the service should support JSONP as well. If the script returns a JSON object like this:

{a: 0, b: 1}

The object will be evaluated but nothing happens. But JSONP services accept a callback function name something like this

<script type="text/javascript" src="http://path.to/your/javascript?callback=yourCallbackFunction"></script>

and wrap the data as a parameter to your callback like this:

yourCallbackFunction({a: 0, b: 1});

So that the function is called when the script is evaluated.

Answer 3

You can use JSONP. in jQuery, try getJSON: http://api.jquery.com/jQuery.getJSON/

Answer 4

Instead you should use a local proxy. Set up a asp.net/php page that will load the remote page on the back end and then use ajax to load the proxy page.