https://github.com/whatwg/html/pull/3800https://github.com/dtapuska/useractivation
Add a new Window.postMessage override that takes a dictionary as a 3rd argument.
In order to add additional arguments to postMessage a dictionary should be allowed to be passed in, this provides for maximum flexibility. It also aligns the other types of post message to the following pattern (message, transferrables, options)
We'd like to be able to optionally specify if an iframe can propagate it's user activation information to the receiver of the postMessage. In order to do this we feel we need to add an argument to postMessage. Since postMessage doesn't take a dictionary this is a stepping stone in doing that.
Firefox: No public signals
Edge: No public signals
Safari: No public signals
Web developers: No signals
Low. Detecting presence of the new API is easy by checking the length of the function.
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