<div class="searchBox">
  <div class="search">
    <ion-icon name="search-outline"></ion-icon>
  </div>
  <div class="searchInput">
    <input type="text" placeholder="输入你要查找的内容">
  </div>
  <div class="close">
    <ion-icon name="close-outline"></ion-icon>
  </div>
</div>
<script type="module" src="https://unpkg.com/ionicons@5.5.2/dist/ionicons/ionicons.esm.js"></script>
<script nomodule src="https://unpkg.com/ionicons@5.5.2/dist/ionicons/ionicons.js"></script>

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Ubuntu', sans-serif;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: #6aa7d4;
  background: linear-gradient(45deg,#4E65FF ,#92EFFD);
}

.searchBox {
  position: relative;
  width: 60px;
  height: 60px;
  background: #fff;
  display: flex;
  justify-content: space-between;
  transition: 0.5s;
  overflow: hidden;
  box-shadow: 0 25px 35px rgba(0,0,0,0.1);
}

.searchBox.active {
  width: 360px;
}

.search {
  position: relative;
  width: 60px;
  height: 60px;
  display: flex;
  color: #333;
  justify-content: center;
  align-items: center;
  font-size: 1.5em;
  cursor: pointer;
}

.close {
  position: absolute;
  right: 0;
  width: 50px;
  height: 60px;
  display: flex;
  color: #333;
  justify-content: center;
  align-items: center;
  scale: 0;
  cursor: pointer;
  font-size: 1.25em;
  transition: 0.5s;
  transition-delay: 0s;
}

.searchBox.active .close {
  scale: 1;
  transition-delay: 0.5s;
}

.searchInput {
  position: absolute;
  left: 60px;
  width: calc(100% - 120px);
  height: 100%;
  line-height: 60px;
  background: #f00;
}

.searchInput input {
  position: absolute;
  width: 100%;
  height: 100%;
  border: none;
  outline: none;
  font-size: 1.25em;
}

const search = document.querySelector('.search');
const close = document.querySelector('.close');
const searchBox = document.querySelector('.searchBox');
search.onclick = function(){
  searchBox.classList.add('active');
}
close.onclick = function(){
  searchBox.classList.remove('active');
}