How to change value after delay by using angularjs?

Try using: $timeout

Angular’s wrapper for window.setTimeout. The fn function is wrapped
into a try/catch block and delegates any exceptions to
$exceptionHandler service.

$timeout(fn[, delay][, invokeApply]);

Updated Fiddle

JavaScript

var app = angular.module('miniapp', []);

function Ctrl($scope, $timeout) {  
     $scope.val = false;
     $timeout(function(){$scope.val = true}, 3000);       
}