jQuery addClass example

Change class name on click in jQuery

HTML

<div class="cricles">
  <span>32</span>
  <span class="text">Длинное слово</span>
  <span class="text">Слово</span>
</div>

CSS

body {
  background: #fff;
  padding: 20px;
  font-family: sans-serif;
}

.cricles::after {
  content: '';
  display: block;
  clear: both;
}

.cricles>span {
  display: block;
  position: relative;
  float: left;
  min-width: 32px;
  height: 32px;
  border: 1px solid #999;
  text-align: center;
  line-height: 34px;
  margin: 0px 20px 0px 0px;
  border-radius: 100px;
  overflow: hidden;
}

.cricles>.text {
  padding: 0px 13px;
}

.cricles>span {
  background: linear-gradient(to left top, transparent calc(50% - 1px), red 50%, transparent calc(50% + 1px));
}

JavaScript

// find elements
var banner = $("#banner-message")
var button = $("button")

// handle click and add class
button.on("click", function() {
  banner.addClass("alt")
})