执行一次对大小写敏感的查找 - 在线编辑器

          <p id="demo">单击显示查找的位置</p>
<button onclick="myFunction()">点我</button>
<script>
  function myFunction() {
    var str = "Mr. Blue has a blue house"
    var n = str.search("blue");
    document.getElementById("demo").innerHTML = n;
  }
</script>
        