对于Knockoutjs本身来说，没有提供验证模块，不过，有第三方的扩展，就像你为jquery库作extensions一样，这讲中我将介绍一个Knockout插件扩展，knockout.validation.js，用它来实现对HTML标记的验证，
下面是它在Github上的地址https://github.com/Knockout-Contrib/Knockout-Validation。这个插件的使用很类似MVC自己的验证，如果你自己手动扩展过它的ValidationAttribute，那么你对下面的JS肯定不会
感到陌生，思想是一样的，JS里的Validation也是面向对象的，也支持override，比如系统为非空验证提供的提供是“This field is required.”，你当然可以重写它，让它显示“请输入用户名”，呵呵，这个很简单，下面
看一下某体的代码：
首先要引入这两个JS文件
<script src="~/Scripts/knockout-2.1.0.js"></script>
<script src="~/Scripts/knockout.validation.min.js"></script>
下面的例子中，分别对用户名，分类ID，价格，Email地址做了数据有效性的验证，并且每个验证中的参数都可以以JS对象或者属性的形式存在，这也足够灵活了，如果是JS对象的话，那么params表示参数的值，而message
表示提示的信息，看一下它的实现（很面向对象的，呵呵）。
<script type="text/ecmascript">
var Product = function () {
var self = this; self.CategoryId = ko.observable().extend({
required: true
}); self.price = ko.observable().extend({
required: { params: true, message: "请输入价格" },
min: { params: , message: "请输入大于1的整数" },
max:
}); self.name = ko.observable().extend({
minLength: ,
maxLength: { params: , message: "名称最大长度为30个字符" },
required: {
params: true,
message: "请输入名称",
}
}); self.Email = ko.observable().extend({
required: {
params: true,
message: "Please enter your email"
},
email: {
params: true,
message: "The format is not correct"
}
}); self.Register = function () {
self.errors = ko.validation.group(self);
if (self.isValid()) {
alert('data sent');
} else {
self.errors.showAllMessages();
}
}; }
var viewModel = new Product();
ko.applyBindings(viewModel); </script>
下面再看一下HTML部分，它与之前讲的knockout数据绑定没有区别
<fieldset>
<legend>添加商品</legend>
<div class="editor-label">
@Html.LabelFor(model => model.name)
</div>
<div class="editor-field">
<input data-bind='value: name' />
</div> <div class="editor-label">
@Html.LabelFor(model => model.price)
</div>
<div class="editor-field">
<input data-bind='value: price' /><!-- uniqueName: true表示表单的name是唯一的-->
<div class="editor-label">
@Html.LabelFor(model => model.CategoryId)
</div>
</div>
<div class="editor-field">
<input data-bind='value: CategoryId' />
</div>
<p>
<input type="button" value="Create" data-bind="click:Register" />
</p>
</fieldset>
事实上，比上面的知识更重要的是，我认为还是它的思想，这样东西都可以由前台工程师去开发，然底层开发人员（asp,.net,php,jsp,ios,android)不需要去干预这些，它们只要写好JS文件去调用自己的方法即可，当然JS文件也可以以前台工程师去写，只不
过，这需要前台工程师等底层工程师把接口写好后，再开发了，呵呵。
看一下效果：
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iG3fTw4MwE1OLcVLLSxbMEA8Dt7hMMf/39TyYwNnz9zwTD2kGDYABY5eHBUFLsthFD4Y9gAFjlDk8lbQiGu0wlCQaAR1gdDMlOvCQYMoVsCwZTSQCPsOU3n5MbM115cu/03LkDCgsUDAB34W8lARARDABEBAMAEcEAQEQwABARDABEBAMAEcEAQEQwABARDABEBAMAke7HB3j2hwzwSrpnXwAAbREMAEQEAwARwQBARDAAEPk/6aZ8TuF5DAIAAAAASUVORK5CYII=" alt="" />
怎么样，有点MVC的味道吧，呵呵，这个前台validation的表现可以由CSS工程师去搞定，不过，一般这活都是前台工程师的，嗨，前台工程师要负责的东西可真不少PS切图，HTML代码编写，JS代码编写，CSS样式编写，还有如果是MVVM架构，
他们还要了解数据库结构，呵，在这里，让我代表所有开发人员说一声：“前台工程师，你们辛苦了”！