How to restrict users to only pick from calendar icon

[samadam]

I have a date field which I want to restrict users from manually entering the values instead only use the calendar icon to pick. Is this possible?

[Joe Wong]

Do you want this restriction within Service Portal?

[samadam]

On the portal. 

[Brad Bowman · Accepted solution]

Another approach is to use a UI Policy with Run scripts and On load checked, and Isolate script unchecked.  Use a script like this in the Execute if true box

function onCondition() {
	var $ = this.jQuery;
	$('input[id="table_name.field.name"]').attr('readonly', true);
}

[samadam]

Perfect, that worked. Thank you