代码示例:(标识:eg_js_string_tolowercase)
<!DOCTYPE html>
<html>
<body>

<h1>JavaScript 字符串方法</h1>

<p>把字符串转换为小写:</p>

<button onclick="myFunction()">试一试</button>

<p id="demo">Hello World!</p>

<script>
function myFunction() {
  var text = document.getElementById("demo").innerHTML;
  document.getElementById("demo").innerHTML = text.toLowerCase();
}
</script>

</body>
</html>
运行结果: