jQuery onclick事件没有激发

Question

jQuery的：

$("#addfav").click(function(){
    alert('clicked1');
    $("#addfav").attr('id','delfav');
    $("#star").attr('src','<?php echo base_url()?>assets/images/star_full.png');
    var data = {
        pet_id: $("#addfav").attr('data-num')
    }
    console.log(data);
})
$("#delfav").click(function(){
    alert('clicked2');
    $("#delfav").attr('id','addfav');
    $("#star").attr('src','<?php echo base_url()?>assets/images/star_empty.png');
    var data = {
        pet_id: $("#delfav").attr('data-num')
    }
    console.log(data);
})

HTML：

<span data-num="42103" id="addfav" style="cursor:pointer"><img id="star" src="http://newseinstein.com/Rwork/assets/images/star_full.png" alt=""></span>

总是提醒clicked1有人可以帮助我为什么会这样？