CSS

此繫結將提供的 CSS 類應用於該元素。當給定條件被鬆散地評估為真時，將應用靜態類。動態類使用可觀察或計算的值。

page.html 中

<p data-bind="css: { danger: isInDanger }">Checks external expression</p>
<p data-bind="css: { danger: dangerLevel() > 10 }">Expression can be inline</p>
<p data-bind="css: { danger: isInDanger, glow: shouldGlow }">Multiple classes</p>
<p data-bind="css: dynamicObservable">Dynamic CSS class from observable</p>
<p data-bind="css: dynamicComputed">Dynamic CSS class from computed</p>

page.js

ko.applyBindings({
  isInDanger: ko.observable(true),
  dangerLevel: ko.observable(5),
  isHot: ko.observable(true),
  shouldGlow: ko.observable(true),  
  dynamicObservable: ko.observable('highlighted'),
  dynamicComputed: ko.computed(function() {
        var customClass = "";
        if(dangerLevel() >= 15 ) {
            customClass += " danger";
        }
        if(dangerLevel() >= 10) {
            customClass += " glow";
        }
        if(dangerLevel() >= 5) {
            customClass += " highlighted";
        }
        return customClass;
    });
});

page.css

.danger { background: red; }
.glow { box-shadow: 5px 5px 5px gold; }
.highlighted { color: purple; }

另見： 官方文件 。