How to open a new completely different website using a html input tag and javascript?

Question

I am creating a basic assistant using javascript and html.

First, I want to open a completely different webpage.

Code:

<!--HTML5-->
<input type="text" id="gmail">

//javascript
var x = document.getElemntById("gmail").value;

if ( x == "OPEN GMAIL" ) {
//open www.gmail.com
}

The code above means that in the input box, if the user types "OPEN GMAIL", it should open gmail.

Is there any way to do that using javascript? Do I have to use a javascript library ( which one? ) or an altogether new language?