var attaches=[1,2,3]  attaches.length==1?'oneImgs':attaches.length==4?'fourImgs':'otherImgs'    结果并不是'otherImgs' 最后找到解决办法,在后边的三目运算加上括号才可以:attaches.length==1?'oneImgs':(attaches.length==4?'fourImgs':'otherImgs')