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

<p>请单击按钮,在字符串中每行的开头对“is”进行多行搜索。</p>

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

<p id="demo"></p>

<script>
function myFunction() {
  var str = "\nIs th\nis it?";
  var patt1 = /^is/m;
  var result = str.match(patt1);
  document.getElementById("demo").innerHTML = result;
}
</script>

</body>
</html>
运行结果: