js 重复调用的问题？

Question

这个问什么setInterval没有重复调用函数？<script type="text/javascript">function C(){this.test = "abc";}var c = new C();C.prototype.xx = function(obj){console.log(obj.test);}c.xx(c);c.xx(c);c.xx(c);c.xx(c);c.xx(c);c.xx(c);setInterval(c.xx(c),50);</script>

Answer 1

setInterval(function() {
    c.xx(c);
},50);