Can not set readonly on input field in IE

Okay, this is bizarre: If you make the field read-only while it has focus, IE11 seems to go a bit bonkers, and one of the ways it goes bonkers is to let you keep modifying the field while the cursor is there — with some keystrokes, but not others. Here's an example: Fiddle

$("#myInput").one("click", function(e) {
    $(e.currentTarget).prop('readonly', true);
    display("e.currentTarget.readOnly: " + e.currentTarget.readOnly);
});
$("#myInput").on("keydown", function(e) {
    display("e.currentTarget.readOnly: " + e.currentTarget.readOnly);
});
function display(msg) {
    $("<p>").html(String(msg)).appendTo(document.body);
}

Adding this line before setting readOnly fixes it (fiddle):

$(e.currentTarget).blur();

Side note: You don't need jQuery to set the readOnly property, just:

e.currentTarget.readOnly = true; // Note the capital O