How do I use Access-Control-Allow-Origin? Does it just go in between the html head tags?

html cross-domain same-origin-policy access-control cors

186,466

Solution 1

That is an HTTP header. You would configure your webserver or webapp to send this header ideally. Perhaps in htaccess or PHP.

~~Alternatively you might be able to use~~

<head>...<meta http-equiv="Access-Control-Allow-Origin" content="*">...</head>

I do not know if that would work. Not all HTTP headers can be configured directly in the HTML.

This works as an alternative to many HTTP headers, but see @EricLaw's comment below. This particular header is different.

Caveat

This answer is strictly about how to set headers. I do not know anything about allowing cross domain requests.

About HTTP Headers

Every request and response has headers. The browser sends this to the webserver

GET /index.htm HTTP/1.1

Then the headers

Host: www.example.com
User-Agent: (Browser/OS name and version information)
.. Additional headers indicating supported compression types and content types and other info

Then the server sends a response

Content-type: text/html
Content-length: (number of bytes in file (optional))
Date: (server clock)
Server: (Webserver name and version information)

Additional headers can be configured for example Cache-Control, it all depends on your language (PHP, CGI, Java, htaccess) and webserver (Apache, etc).

Solution 2

There are 3 ways to allow cross domain origin (excluding jsonp):

Set the header in the page directly using a templating language like PHP. Keep in mind there can be no HTML before your header or it will fail.
Modify the server configuration file (apache.conf) and add this line. Note that "*" represents allow all. Some systems might also need the credential set. In general allow all access is a security risk and should be avoided:

Header set Access-Control-Allow-Origin "*" Header set Access-Control-Allow-Credentials true
To allow multiple domains on Apache web servers add the following to your config file
SetEnvIf Origin "http(s)?://(www\.)?(example.org|example.com)$" AccessControlAllowOrigin=$0$1 Header add Access-Control-Allow-Origin %{AccessControlAllowOrigin}e env=AccessControlAllowOrigin Header set Access-Control-Allow-Credentials true
For development use only hack your browser and allow unlimited CORS using the Chrome Allow-Control-Allow-Origin extension
Disable CORS in Chrome: Quit Chrome completely. Open a terminal and execute the following. Just be cautious you are disabling web security:

open -a Google\ Chrome --args --disable-web-security --user-data-dir

Solution 3

If you use Java and spring MVC you just need to add the following annotation to your method returning your page :

@CrossOrigin(origins = "*")

"*" is to allow your page to be accessible from anywhere. See https://developer.mozilla.org/fr/docs/Web/HTTP/Headers/Access-Control-Allow-Origin for more details about that.

Solution 4

<?php header("Access-Control-Allow-Origin: http://example.com"); ?>

This command disables only first console warning info

console

Result: console result

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Author by

davis

SOreadytohelp

Updated on April 11, 2021

Comments

davis about 3 years
I've been reading about Access-Control-Allow-Origin because it seems effective at allowing cross domain requests since I have access to the external site. My question ism how do I use Access-Control-Allow-Origin to allow cross domain requests. I tried this (don't laugh) (by the way all I want is for a single number, 1 or 0 to be returned)
```
<html>
<head>
Access-Control-Allow-Origin: *
</head>
<body>
1
</body>
</html>
```
Am I close? Thanks for your help. If there is an easier way to do a simple cross-domain request let me know.