toggle show/hide div with button?

Hopefully this is an easy question. I have a div that I want to toggle hidden/shown with a button

<div id="newpost">

Pure JavaScript:

var button = document.getElementById('button'); // Assumes element with id='button'

button.onclick = function() {
    var div = document.getElementById('newpost');
    if (div.style.display !== 'none') {
        div.style.display = 'none';
    }
    else {
        div.style.display = 'block';
    }
};

SEE DEMO

jQuery:

$("#button").click(function() { 
    // assumes element with id='button'
    $("#newpost").toggle();
});

SEE DEMO

Look at jQuery Toggle

HTML:

<div id='content'>Hello World</div>
<input type='button' id='hideshow' value='hide/show'>

jQuery:

jQuery(document).ready(function(){
    jQuery('#hideshow').live('click', function(event) {        
         jQuery('#content').toggle('show');
    });
});

For versions of jQuery 1.7 and newer use

jQuery(document).ready(function(){
    jQuery('#hideshow').on('click', function(event) {        
        jQuery('#content').toggle('show');
    });
});

For reference, kindly check this demo