JavaScriptで文字列を検索する方法は？

以下はJavaScriptで文字列を検索するためのコードです-

例

<!DOCTYPE html>
<html lang="en" >
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .result {
      font-size: 20px;
      font-weight: 500;
   }
</style>
</head>
<body>
<h1>Searching a string in JavaScript</h1>
<div class="sample">The spring season is about to come.</div>
<div style="color: green;" class="result"></div>
<button class="btn">CLICK HERE</button>
<h3>
Click on the above button to find the string 'spring' in the above string
</h3>
<script>
   let btnEle = document.querySelector(".btn");
   let sampleEle = document.querySelector(".sample").innerHTML;
   let resEle = document.querySelector(".result");
   btnEle.addEventListener("click", () => {
      resEle.innerHTML = "The string spring is found at position " + sampleEle.search("spring");
   });
</script>
</body>
</html>