greasemonkey script to invert colors of cruise control builds view every 7 seconds

cruisecontrol-flipcolors.user.js

// ==UserScript==
// @name           cruisecontrol-flipcolors
// @namespace      cruisecontrol-flipcolors
// @description    invert colors of cruise control builds view every 7 seconds
// @include        http://*cruisecontrol*/dashboard/tab/builds
// ==/UserScript==

function addGlobalStyle(css) {
    var head, style;
    head = document.getElementsByTagName('head')[0];
    if (!head) { return; }
    style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css;
    head.appendChild(style);
    return style;
}

function changeCssByTag(tagName, cssKey, cssValue) {
	var list = document.getElementsByTagName(tagName)
	for(i in list) { obj = list[i]
		obj.style[cssKey]=cssValue
	}
}

window.addEventListener('load', 
function() { 
	document.getElementById('header').style.display='none';
	document.getElementById('project_summary_panel').style.display='none';
	document.getElementsByTagName('body')[0].style.overflow = 'hidden';
	changeCssByTag('img', 'display', 'none');

	addGlobalStyle('.no_decoration ' +
		'{ color: inherit ! important; }');
	addGlobalStyle('.passed, .failed ' +
		'{ background-image: url() ! important; }');

//	.inactive, .discontinued, .unknown #666666 #CCCCCC
//	.passed #003300 #B6FFB1
//	.failed #330000 #FFC2C9
	passed_inverse =
		'.passed, .passed a.clickable_target ' +
		'{ color: #FFCCFF ! important; background-color: #49004E ! important; }'
	failed_inverse = 
		'.failed, .failed a.clickable_target ' +
		'{ color: #CCFFFF ! important; background-color: #003D36 ! important; }'
	inactive_inverse = 
		'.inactive, .discontinued, .unknown, ' +
		'.inactive a.clickable_target, ' +
		'.discontinued a.clickable_target, ' +
		'.unknown a.clickable_target ' +
		'{ color: #999999 ! important; background-color: #333333 ! important; }'
	body_inverse = 'body, .tabContent { background-color: #000000 ! important }'

	passed = addGlobalStyle(passed_inverse)
	failed = addGlobalStyle(failed_inverse)
	inactive = addGlobalStyle(inactive_inverse)
	body = addGlobalStyle(body_inverse)

	setInterval(function () {
		passed.innerHTML   = passed.innerHTML   ? '' : passed_inverse;
		failed.innerHTML   = failed.innerHTML   ? '' : failed_inverse;
		inactive.innerHTML = inactive.innerHTML ? '' : inactive_inverse;
		body.innerHTML     = body.innerHTML     ? '' : body_inverse;
		changeCssByTag('img', 'display', 'none');
	}, 7000)

},
true);