Multiple buttons and javascript

Hi,

I am willing to place a button which, after it is pressed, displays other elements, so far I got that done without any problem. The hard part starts if I want to have few of those buttons and each of them to display/hide other content.

My javascript code which hides/shows content is:

<script>
function fade(div_id, button) {

    if(button.value == 'Show content') {
        $('#'+div_id).fadeIn('slow');
        button.value = 'Hide content';
    }
    else {
        $('#'+div_id).fadeOut('slow');
        button.value = 'Show content';
    }
}
</script>

The code for my button is simple input tag:

<input type="button" onclick="fade('content-div-id', this)" value="Hide content" class="content-button">

The problem is that the value of buttons change to the same as others after it is pressed, how should I modify the code above to make it work for multiple buttons?

PS. I am attaching html file to illustrate my problem.