<link href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"></script>
<style>
.ng-scope span{display:inline}
.red{color:#ff0000;font-size:50px;text-transform:uppercase;text-decoration:blink;}
.bg-custom{background:#999;color:#fff;width:100%;float:left;padding:25px;}
</style>
</head>
<body>
<div ng-app="login" ng-controller="changecolor" class="bg-custom">
<p>My name is <span id="me" data-ng-bind="name || 'Don'" ></span></p>
<input type="text" ng-change='hello()' id='Text1' ng-model="name" placeholder="you are wrong">
</div>
<script>
var app = angular.module('login', []);
app.controller('changecolor', function($scope) {
$scope.hello= function(){
var x=angular.element(document.getElementById('Text1'));
$scope.textbox = x.val();
var bool = angular.equals($scope.textbox, 'you are wrong');
if(bool==true)
{
var redclass = angular.element( document.querySelector( '#me' ) );
redclass.addClass('red');
redclass.removeClass('black');
}
else
{
