Why can't I paste text to the clipboard on IOS?

Question

JavaScript

I'm trying to paste text into the clipboard with: Checking with:
event.clipboardData.setData('text/plain', myText);

console.log(event.clipboardData.getData("text/plain"));

Returns an empty string - nothing.
This kind of pasting is needed to keep track of any text selection and copying by the user, so "document.execCommand("copy");" does not fit.
Also, this approach does not work, it does not paste the text into the clipboard, in FF browsers it sees that "event.clipboardData" is undefined, IE does not accept either window.clipboardData.setData or event.clipboardData.setData.