It turns out that such functionality could not be achieved, because of general limitations. The HTML Input element has 3 keyboard DOM events: onkeydown, onkeypress, and onkeyup.
fires before keypress, when a key on the keyboard is pressed.
fires after keydown, when a key on the keyboard is pressed or hold. This means that if the user holds a key for a while, onkeypress will fire several times.
fires when a key on the keyboard is released.
On onkeydown event we could not say how much time the user will hold the key, and because of this we could not say what will be the updated text.
As an alternative for showing autocomplete/autosuggest options onkeyup
DOM event of the input can be used.
the Telerik team
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