Changing button text onclick

When I click on myButton1 button, I want the value to change to Close Curtain from Open Curtain.
HTML:

<input onclick="change()" type="button" value="Open Curtain" id="myButton1"></input>

Javascript:

function change();
{
    document.getElementById("myButton1").value="Close Curtain";
}

The button is displaying open curtain right now and I want it to change to close curtain, is this correct?

Answer

If I’ve understood your question correctly, you want to toggle between ‘Open Curtain’ and ‘Close Curtain’ — changing to the ‘open curtain’ if it’s closed or vice versa. If that’s what you need this will work.

function change() // no ';' here
{
    if (this.value=="Close Curtain") this.value = "Open Curtain";
    else this.value = "Close Curtain";
}

Note that you don’t need to use document.getElementById("myButton1") inside change as it is called in the context of myButton1 — what I mean by context you’ll come to know later, on reading books about JS.

UPDATE:

I was wrong. Not as I said earlier, this won’t refer to the element itself. You can use this:

function change() // no ';' here
{
    var elem = document.getElementById("myButton1");
    if (elem.value=="Close Curtain") elem.value = "Open Curtain";
    else elem.value = "Close Curtain";
}