How to block writing in input text?

Give your element the readonly attribute, this will disallow users to type anything into it. However, you will still be able to write to add through javascript for example when a date is chosen. Here is an example:

<input type="text" id="txt" readonly="readonly">

JavaScript:

var el = document.getElementById('txt');
el.value = "Testing......";

Working Demo

<input type="text" id="someId" disabled="disabled" />

The disabled property will prevent any user input, but you can still write to it via your javascript calendar method.

For those who wants to prevent typing but not having the disabled style, can try:

<input type="text" onkeypress="return false;"/>