I am trying to access this address:
http://52.208.91.209:3000/?paging=1
Accessing manually works fine.
Accessing via an Angular 4 request returns:
No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access.
I have googled it for a few hours and did not find a solution.
The only "solution" I have found is using Allow-Control-Allow-Origin plugin.
The address I am trying to access is not mine.
I am just trying to work with it.
I have even read about proxies when using ng serve with angular CLI but didnt fully understand.
All of the solutions I saw are simply a response headers problem on the server side. However, This is NOT my server so I cannot configure it.
Any help would be appreciated. Thank you.
You can change your frontend JavaScript code to instead make the request through a public proxy.
To try that, change your code to use the following URL:
https://cors-anywhere.herokuapp.com/http://52.208.91.209:3000/?paging=1
That’ll cause the request to go to https://cors-anywhere.herokuapp.com, a open CORS proxy that sends the request on to the http://52.208.91.209:3000/?paging=1 URL you want.
That proxy gets the response, takes it and adds the Access-Control-Allow-Origin response header to it, and then finally passes that back to your requesting frontend code as the response.
So in the end because the browser sees a response with the Access-Control-Allow-Origin response header, the browser allows your frontend JavaScript code to access the response.
Or use the code from https://github.com/Rob--W/cors-anywhere/ or such to set up your own proxy.
You need a proxy in this case because http://52.208.91.209:3000/?paging=1 itself doesn’t send the Access-Control-Allow-Origin response header—and in that case your browser will not allow your frontend JavaScript code to access a response from that server cross-origin.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS has more details.
You can't access that API the way you want to from the browser. There are security measures in place to prevent this from happening. If you do not control the source of the data, you cannot do anything to fix this. Your only option is to have your own server request the data, and you then go through your server to get the data.
Edit: You actually can do this if you only plan to run it locally. Chrome has flags to ignore this security measure. If you don't plan on using this on any machine other than your own, you can force chrome to allow this locally.
The solution I've found was to build my project with the right host using
ng build --production -host=myDomain.com
Related
This is a research question I've been hitting my head on for a while now. I'm not sure if it's possible but it seems like it should be.
How do I make var token that was defined in them.com's javascript to be visible to us.com's javascript WITHOUT sending information to any of the two servers?
The goal is to save information in the browser to be accessible cross-domain? localStorage, sessionStorage are domain-locked. And set-cookie make it visible to the server... So I cannot use those.
You could give CORS Anywhere a shot.
https://cors-anywhere.herokuapp.com/
CORS Anywhere is a NodeJS proxy which adds CORS headers to the proxied request.
Basically, you can prefix the request URL with https://cors-anywhere.herokuapp.com/.
For example:
fetch('https://cors-anywhere.herokuapp.com/http://your-req-url.com/some-endpoint')
You can also host it yourself. Further reading: https://github.com/Rob--W/cors-anywhere/
I am working on a project where I was given an endpoint to get some data. I put that endpoint's url in the browser, and I see JSON as expected. I make the same request in Postman, and I get the expected result. Then, making the request using fetch or axios from localhost in a React app, when I run the app in the browser I get a:
Access to fetch at 'https://providedurl/path' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
I just want to make sure there is nothing I can do about this? Is the only solution to have the endpoint be modified to add the Access-Control-Allow-Origin header, or is there something that can be done from the request side?
CORS (Cross-Origin Resource Sharing) is a way for the server to say “I will accept your request, even though you came from a different origin.” This requires cooperation from the server – so if you can’t modify the server (e.g. if you’re using an external API), this approach won’t work.
Modify the server to add the header Access-Control-Allow-Origin: * to enable cross-origin requests from anywhere (or specify a domain instead of *). This should solve your problem.
But you are able to access it in Postman and browsers, if you can disable the CORS in browser level it will work.
Disable CORS in Chrome:
Create a new shortcut for the chrome browser and rename to "anyname(disablecors)"
Right click on new created shortcut and select properties
Create a folder in your system with any name(tempchrome).
Select shorcut tab and add target as ""[PATH_TO_CHROME]\chrome.exe" --disable-web-security --disable-gpu --user-data-dir= "path of the tempchrome""
Click on apply and save.
Open your application in newly created chrome shortcut(disablecors)
Another quick fix in case you have front end running on port 3000 and backend on 5000 is to apply proxy.
It goes like this. Put in your client package the following above dependencies:
"proxy": "http://localhost:5000",
Then make the request relative, NOT absolute. Should work with this setup.
I need to open a local html file in the browser. The javascript works fine but ajax stops working and XMLHttpRequest gives a cross origin error. Is there a way to run ajax from local directory. It is necessary for me that it is run from local file only.
Thanks
For anyone who wants to know, I had to run a server in the app to serve the js files. Seems like it's not possible to do it without running a server.
If anyone knows of another way, do tell.
The simplest way to allow this in Firefox is to navigate to about:config, look for the privacy.file_unique_originsetting and toggle it off.
Essentially, Firefox used to treat local files from the same directory as being from the same source, thus CORS was happily satisfied. That behavior changed after CVE-2019-11730 was discovered.
It worked fine for me on 84.0.1 on Arch. Just be sure to turn it off when not locally debugging.
Source
If you are using VS Code, the Live Server extension might help you. It resolved a cross-origin issue I was having when editing a webpage.
https://marketplace.visualstudio.com/items?itemName=ritwickdey.LiveServer
If you are using chrome, try this extension
CORS allows web applications on one domain to make cross domain AJAX requests to another domain. It's dead simple to enable, only requiring a single response header to be sent by the server.
What this extension does is add to response header rule - Access-Control-Allow-Origin: *
You can do that manually also by sending a response header.
For simple CORS requests, the server only needs to add the following header to its response: Access-Control-Allow-Origin: *
Read this for more info.
If you are able to change the server code, you can try adding the string "null" to allowed origins. In Chrome, it sends the origin as "null" if it's running from a local file.
Here's an example in ASP.NET Core for setting up the "null" origin:
services.AddCors(options =>
{
options.AddPolicy("InsecurePolicy",
builder => builder
.WithOrigins("null")
.AllowAnyMethod()
.AllowAnyHeader()
.AllowCredentials());
});
Note that this is not recommended, but might be good enough if you just need it during development.
I want a simple javascript script that exists on my localhost to make a connection to another domain(eg: anotherdomain.com) with ajax and get the response , but all my browsers tell me that error of (connection blocked , Reason: CORS header 'Access-Control-Allow-Origin' missing)
but when I check the network traffic with network monitor program like (fiddler), I see that the response already came from the server at (anotherdomain.com) to my local machine , it is just my browser who is blocking me from getting it !!
1- can I order my browser to ignore the CORS rules using javascript code?
2- what is my options to overcome this problem? is building a custom client disktop application with c# to send and receive requests freely is the best way to do it?
3- is CORS policy designed to protect the web clients or the web servers ?
thank you, and please consider that I'm complete newbie in web
but when I check the network traffic with network monitor program like (fiddler), I see that the response already came from the server at (anotherdomain.com) to my local machine , it is just my browser who is blocking me from getting it !!
Well for sure, the connection was estabilished to check the presence of the header you mentioned, but data was unlikely to be transferred.
Regarding your questions,
There are 2 options actually. One is to set the Access-Control-Allow-Origin header with proper origin according to yours. The second is to make a JSONP call, though the response of server must support such a solution.
The best option is to have a server with the above header specified. Your server would handle all the network stuff on its side and your script would just get/send some responses/requests.
I would say it designed more to protect the server. Imagine the following situations. Your script on your site makes a lot of POST requests to the another site. Actions like submitting forms etc. could happen and would be allowed. That's harmful, right? You can read about that in this stack question.
I am trying to use $.getJSON with a local app calling another local app on a different port.
For example my app is running on localhost:3000, but I want to make a $.getJSON call to another app running on localhost:3001, in firebug it returns red with a 200 response, but with no data in the response. Is there a way to do this? I tried this....
$.getJSON('http://localhost:3001/dashboard/widgets/marketing_efficiency_gauge.json',
{ key: 'value' }, function(data){
alert(data)
});
Edit: for clarity there are two rails apps involved one on localhost:3000 another on localhost:3001
Second edit: here is the json response for localhost:3001 when I hit it with a browser (say firefox) https://gist.github.com/willfults/7665299
The Same Origin Policy prevents JavaScript scripts from making HTTP requests to different domains. For the purposes of SOP, a URL with the same hostname but different ports (as is the case here) is still considered to be a different domain, and hence requests are not permitted.
What typically happens in such cases is that the browser actually does make the request over the network, but drops the response and sends an error result to the JavaScript.
To fix this, you'll need to implement Cross-Origin Resource Sharing on the localhost:3001 service. In a nutshell, this entails adding a Access-Control-Allow-Origin header to responses listing the domains which are permitted to make cross-domain requests to the service. That is, in this case adding a Access-Control-Allow-Origin: localhost:3000 header to the response from the localhost:3001 service should allow things to work as you expect.
Incidentally, this is why the browser makes the request but drops the result: it needs to request the headers from the server in order to determine whether the JavaScript is allowed to make the request or not (i.e. it needs to check if there's a Access-Control-Allow-Origin header in the response). Why a HEAD request isn't sufficient, I don't know.
The other alternative is to use JSONP. This is potentially simpler to implement on the server side, but has the disadvantages of only working for GET requests, and requiring slightly trickier coding on the client side.