Guide to send requests across different domains

Question

Guide to send requests across different domains

When it comes to web browser security, making cross domain requests is usually disallowed. I recently came across some advice in a book that suggests using XMLHTTPRequest only if you can host the files on the same domain as the requested page. If this isn't possible, it recommends looking for alternative methods.

Now, my questions are:

What alternatives exist for cross-domain requests instead of XMLHTTPRequest?
How does WebSockets fit into this equation? Can it be used for cross-domain requests?

UPDATE: I'm still unclear about this...

For instance, if I fetch a page from www.domain1.com and need to get some JavaScript code from www.domain2.com, my fetched page would need to include something like:

<script src="www.domain2.com/script.js"></script>

in order to circumvent cross domain restrictions.

Alternatively, I could utilize JSONP by making a request like:

However, I wonder: Does this approach escape cross domain limitations since I'm essentially pulling JS from a different domain?

javascript websocket xmlhttprequest cross-domain

Answer 1

Answer №1

To enable cross domain requests, utilize the XMLHttpRequest object along with "Cross Origin Resource Sharing". For more details, refer to: http://en.wikipedia.org/wiki/Cross-origin-resource-sharing

Essentially, the server can specify a Access-Control-Allow-Origin header in its response to either permit or reject the request. The browser will then assess this header and proceed based on its permissions. If not allowed, the browser will terminate the request.

Further information and a practical demonstration are accessible here:

While JSONP serves as an alternative solution, some may consider it somewhat of a workaround.

Answer 2

To enable cross domain requests, utilize the XMLHttpRequest object along with "Cross Origin Resource Sharing". For more details, refer to: http://en.wikipedia.org/wiki/Cross-origin-resource-sharing

Essentially, the server can specify a Access-Control-Allow-Origin header in its response to either permit or reject the request. The browser will then assess this header and proceed based on its permissions. If not allowed, the browser will terminate the request.

Further information and a practical demonstration are accessible here:

While JSONP serves as an alternative solution, some may consider it somewhat of a workaround.

Answer 3

Answer №2

Performing a cross-domain AJAX request

In order to use JSONP, your web service must allow method injection.

It is important to note that your code should function properly when both your web services and web application are on the same domain.

When using $.ajax with dataType: 'jsonp', jQuery adds an additional parameter to the query URL.

For example, if your URL is

http://10.211.2.219:8080/SampleWebService/sample.do

, jQuery appends ?callback={some_random_dynamically_generated_method} to it.

This dynamically generated method acts as a proxy attached to the window object. It serves as a reference to the success function specified in $.ajax, allowing it to call the success method accordingly.

window.some_random_dynamically_generated_method = function(actualJsonpData) {
    //here actually has reference to the success function mentioned with $.ajax
    //so it just calls the success method like this: 
    successCallback(actualJsonData);
}

For more information, refer to the following link:

Make cross-domain ajax JSONP request with jQuery

Answer 4

Performing a cross-domain AJAX request

In order to use JSONP, your web service must allow method injection.

It is important to note that your code should function properly when both your web services and web application are on the same domain.

When using $.ajax with dataType: 'jsonp', jQuery adds an additional parameter to the query URL.

For example, if your URL is

http://10.211.2.219:8080/SampleWebService/sample.do

, jQuery appends ?callback={some_random_dynamically_generated_method} to it.

This dynamically generated method acts as a proxy attached to the window object. It serves as a reference to the success function specified in $.ajax, allowing it to call the success method accordingly.

window.some_random_dynamically_generated_method = function(actualJsonpData) {
    //here actually has reference to the success function mentioned with $.ajax
    //so it just calls the success method like this: 
    successCallback(actualJsonData);
}

For more information, refer to the following link:

Make cross-domain ajax JSONP request with jQuery

Answer 5

Answer №3

If you have data to transmit that doesn't need to be secure (public information), an easy solution is to utilize a CORS proxy. This method will not require any changes to your code or the server side, especially if it's a third-party server like the Yahoo API or OpenWeather. I personally tried using this technique to fetch JSON files with an XMLHttpRequest and had success.

Answer 6

If you have data to transmit that doesn't need to be secure (public information), an easy solution is to utilize a CORS proxy. This method will not require any changes to your code or the server side, especially if it's a third-party server like the Yahoo API or OpenWeather. I personally tried using this technique to fetch JSON files with an XMLHttpRequest and had success.

Guide to send requests across different domains

Answer №1

Answer №2

Answer №3

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