Download The Mask: The Origin [BETTER]
For example, about:blank is often used as a URL of new, empty popup windows into which the parent script writes content (e.g. via the Window.open() mechanism). If this popup also contains JavaScript, that script would inherit the same origin as the script that created it.
download The Mask: The Origin
Modern browsers usually treat the origin of files loaded using the file:/// schema as opaque origins. What this means is that if a file includes other files from the same folder (say), they are not assumed to come from the same origin, and may trigger CORS errors.
Note that the URL specification states that the origin of files is implementation-dependent, and some browsers may treat files in the same directory or subdirectory as same-origin even though this has security implications.
Warning: The approach described here (using the document.domain setter) is deprecated because it undermines the security protections provided by the same origin policy, and complicates the origin model in browsers, leading to interoperability problems and security bugs.
A page may change its own origin, with some limitations. A script can set the value of document.domain to its current domain or a superdomain of its current domain. If set to a superdomain of the current domain, the shorter superdomain is used for same-origin checks.
Afterward, the page can pass the same-origin check with (assuming sets its document.domain to "company.com" to indicate that it wishes to allow that - see document.domain for more). However, company.com could not set document.domain to othercompany.com, since that is not a superdomain of company.com.
The mechanism has some limitations. For example, it will throw a "SecurityError" DOMException if the document-domain Permissions-Policy is enabled or the document is in a sandboxed , and changing the origin in this way does not affect the origin checks used by many Web APIs (e.g. localStorage, indexedDB, BroadcastChannel, SharedWorker). A more exhaustive list of failure cases can be found in Document.domain > Failures.
Note: When using document.domain to allow a subdomain to access its parent, you need to set document.domain to the same value in both the parent domain and the subdomain. This is necessary even if doing so is setting the parent domain back to its original value. Failure to do this may result in permission errors.
JavaScript APIs like iframe.contentWindow, window.parent, window.open, and window.opener allow documents to directly reference each other. When two documents do not have the same origin, these references provide very limited access to Window and Location objects, as described in the next two sections.
Access to data stored in the browser such as Web Storage and IndexedDB are separated by origin. Each origin gets its own separate storage, and JavaScript in one origin cannot read from or write to the storage belonging to another origin.
Cookies use a separate definition of origins. A page can set a cookie for its own domain or any parent domain, as long as the parent domain is not a public suffix. Firefox and Chrome use the Public Suffix List to determine if a domain is a public suffix. Internet Explorer uses its own internal method to determine if a domain is a public suffix. The browser will make a cookie available to the given domain including any sub-domains, no matter which protocol (HTTP/HTTPS) or port is used. When you set a cookie, you can limit its availability using the Domain, Path, Secure, and HttpOnly flags. When you read a cookie, you cannot see from where it was set. Even if you use only secure https connections, any cookie you see may have been set using an insecure connection.
\n Modern browsers usually treat the origin of files loaded using the file:/// schema as opaque origins.\n What this means is that if a file includes other files from the same folder (say), they are not assumed to come from the same origin, and may trigger CORS errors.\n
Afterward, the page can pass the same-origin check with (assuming sets its document.domain to \"company.com\" to indicate that it wishes to allow that - see document.domain for more). However, company.com could not set document.domain to othercompany.com, since that is not a superdomain of company.com.
The mechanism has some limitations. For example, it will throw a \"SecurityError\" DOMException if the document-domain Permissions-Policy is enabled or the document is in a sandboxed , and changing the origin in this way does not affect the origin checks used by many Web APIs (e.g. localStorage, indexedDB, BroadcastChannel, SharedWorker). A more exhaustive list of failure cases can be found in Document.domain > Failures.
HTML provides a crossorigin attribute for images that, in combination with an appropriate CORS header, allows images defined by the element that are loaded from foreign origins to be used in a as if they had been loaded from the current origin.
As soon as you draw into a canvas any data that was loaded from another origin without CORS approval, the canvas becomes tainted. A tainted canvas is one which is no longer considered secure, and any attempts to retrieve image data back from the canvas will cause an exception to be thrown.
If the foreign content comes from an image obtained from either as HTMLCanvasElement or ImageBitMap, and the image source doesn't meet the same origin rules, attempts to read the canvas's contents are blocked.
In this example, we wish to permit images from a foreign origin to be retrieved and saved to local storage. Implementing this requires configuring the server as well as writing code for the website itself.
In short, this configures the server to allow graphic files (those with the extensions ".bmp", ".cur", ".gif", ".ico", ".jpg", ".jpeg", ".png", ".svg", ".svgz", and ".webp") to be accessed cross-origin from anywhere on the internet.
Now that the server has been configured to allow retrieval of the images cross-origin, we can write the code that allows the user to save them to local storage, just as if they were being served from the same domain the code is running on.
The key is to use the crossorigin attribute by setting crossOrigin on the HTMLImageElement into which the image will be loaded. This tells the browser to request cross-origin access when trying to download the image data.
We're using a hard-coded URL (imageURL) and associated descriptive text (imageDescription) here, but that could easily come from anywhere. To begin downloading the image, we create a new HTMLImageElement object by using the Image() constructor. The image is then configured to allow cross-origin downloading by setting its crossOrigin attribute to "Anonymous" (that is, allow non-authenticated downloading of the image cross-origin). An event listener is added for the load event being fired on the image element, which means the image data has been received. Alternative text is added to the image; while does not support the alt attribute, the value can be used to set an aria-label or the canvas's inner content.
imageReceived() is called to handle the "load" event on the HTMLImageElement that receives the downloaded image. This event is triggered once the downloaded data is all available. It begins by creating a new element that we'll use to convert the image into a data URL, and by getting access to the canvas's 2D drawing context (CanvasRenderingContext2D) in the variable context. 350c69d7ab