如何在这些网址中提取变量？

Question

<textarea id=textarea1>
http://life.cuoluo.com/?a=512
http://life.cuoluo.com/l.php?c=1001008&a=10
http://life.cuoluo.com/v.php?a=10&c=1001008&tpcid=12505312 </textarea>
 <script> 
var re=/(?:a\=)(\d+)/g
var arr = textarea1.value.match(re);
for(i=0;i<arr.length;i++)
{
var b=arr[0].replace(re,"$1");
var c=arr[1].replace(re,"$1"); 
var d=arr[2].replace(re,"$1");
 }
alert(b);
alert(c);
alert(d); 
</script>

Answer 1

var s = 'http://life.cuoluo.com/v.php?sfd=3&a=10&c=1001008&tpcid=12505312';
        
    var r = s.match(/[\?|&]a=([^&]+)/);
    
    alert(r[1]);