click

click绑定在DOM元素上添加事件句柄以便元素被点击的时候执行定义的JavaScript函数。大部分是用在button，input上。

<div>
    You've clicked
    <span data-bind="text: numberOfClicks"></span>times
    <button data-bind="click: incrementClickCounter">Click me</button>
</div>

var viewModel = {
        numberOfClicks: ko.observable(0),
        incrementClickCounter: function() {
            var previousCount = this.numberOfClicks();
            this.numberOfClicks(previousCount + 1);
        }
    };

每次点击按钮的时候，都会调用incrementClickCounter()函数，然后更新自动更新点击次数。