Document: queryCommandSupported() method
Deprecated
Avoid using this feature in new projects.
The execCommand() method is "not implemented consistently or fully by user agents, and it is not expected that this will change in the foreseeable future."
This feature may be a candidate for removal from web standards or browsers.
Consider using the following features instead: Async clipboard or contenteditable.
Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.
Note:
Although the execCommand() method is deprecated, if you do decide to use it for reasons given on that page, you should consider checking the command's availability using queryCommandSupported() to ensure compatibility.
The Document.queryCommandSupported() method reports
whether or not the specified editor command is supported by the browser.
Syntax
queryCommandSupported(command)
Parameters
command-
The command for which to determine support.
Return value
Returns a boolean value which is true if the command is supported
and false if the command isn't.
Notes
The 'paste' command return false not only if the feature is
unavailable, but also if the script calling it has insufficient privileges to perform
the action.
Examples
const flg = document.queryCommandSupported("SelectAll");
if (flg) {
// Do something…
}
Specifications
This feature is not part of any current specification. It is no longer on track to become a standard. There is an unofficial W3C execCommand spec draft.