最简单的方法是创建CSS规则的样式表.

The easiest way of doing this is by creating a CSS rule's stylesheet.

在该样式表中，您应该定义 2个类.

In that stylesheet, you should define 2 classes.

让我们假设1是您想要的CSS规则，另一个是默认/无规则.

Let's suppose 1 for your desired CSS rules and the other for the default/none rules.

我只是向您展示该操作的最简单版本，但具有另一个方面.

I am just showing you the simplest version of doing this thing but with another aspect.

$('#b1').on('click', function() {
  $('.c1').removeClass('c1');
  $(this).addClass('c2');
});

.c1 {
  color: red;
}

.c2 {
  color: green;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<button id="b1">Change</button>
<p class="c1">This is a Test Line.</p>