The answer provided by Kevin is the correct one, while the one provided by Shinu answers the questions in the realm of jQuery. Let me explain.
Finding the combobox input with jQuery is no issue and, like Shinu showed, it takes one line. I should not that this exact snippet will disable all inputs of comboboxes on the page, not just one.
However, simply disabling the input may not always be the thing you want. Not to mention there is certain logic in the control (methods, states) that is not activated when using this method. Thus, even though the actual input will look disabled, the control will not know about it, styles wont be applied, events won't be discarded.
And this is why Kevin's answer is the correct one.
All the best,
the Telerik team
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