AngularJS Example:

HTML

<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<div ng-app>
     <h2>Todo</h2>

    <div ng-controller="TodoCtrl">
        <form name="scheduleFrm">
            <input runat="server" id="scheduleIDs" name="scheduleIDs" class="scheduleIds" ng-model="myForm.scheduleIDs" ng-required="true"></textarea>
<span class="error" ng-show="scheduleFrm.scheduleIDs.$error.required">Required</span>

        </form>
    </div>
</div>

CSS

.done-true {
    text-decoration: line-through;
    color: grey;
}

JavaScript

function TodoCtrl($scope) {

    $scope.myForm = {
        //scheduleIDs : 'tst'
    };
}