js里面处理一串数字想把最后2位隐藏

js里面处理一串数字var a = 123456,23456,34567,45678,12121,23232想把这个字符输出没段的最后2位都不显示变成**，b = 123**,234**,345**,456**,121**,232**

&lt;script&gt;<br>var a = &quot;123456,23456,34567,45678,12121,23232&quot;;<br>var b=&quot;&quot;;<br>a = a.split(&quot;,&quot;);<br>for(var i=0; i&lt;a.length; i++){<br>b += a[i].substring(0,a[i].length-2)+&quot;**,&quot;;<br>}<br>b = b.substring(0,b.length-1);<br>alert(b);<br>&lt;/script&gt;