<head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title></title> <script src="js/jquery-1.11.1.min.js"></script> <script src="js/knockout-3.3.0.js"></script> <style> .b_b { background-color: blue; } </style> <script type="text/javascript"> var viewModel = { currentProfit: ko.observable(1) // Positive value, so initially we don‘t apply the "bb" class }; $(function () { viewModel.currentProfit(-1); // Causes the "bb" class to be applied ko.applyBindings(viewModel); }) </script> </head> <body> <div data-bind="css: { ‘b_b‘: currentProfit() < 0 }"> Profit Information </div> </body>
原文：http://www.cnblogs.com/YuanSong/p/4736590.html