AngularJS Example
HTML
<div ng-app="ngSanitize">
<div ng-controller="Ctrl">
Snippet: <textarea ng-model="snippet" cols="60" rows="3"></textarea>
</div>
</div>
CSS
.ng-invalid { border: 1px solid red; }
JavaScript
function Ctrl($scope) {
$scope.snippet =
'<p style="color:blue">an html\n' +
'<em onmouseover="this.textContent=\'PWN3D!\'">click here</em>\n' +
'snippet</p>';
}