字太多用...代替的方法（两种）

$(function() {

        $(".head-pic .user-name").each(function() {

          varmaxwidth = 4;

          if($(this).text().length > maxwidth) {

            varb = $(this).children().is("a");

            if(b) {

              $(this).children().text($(this).children().text().substring(0, maxwidth) +"...");

            }else{

              $(this).text($(this).text().substring(0, maxwidth));

              $(this).text($(this).text() +"..");

            }

          }

        });

      });

overflow:hidden;

white-space:nowrap;

text-overflow:ellipsis; // IE

-o-text-overflow: ellipsis; //Opera

-icab-text-overflow: ellipsis; //iCab

-khtml-text-overflow: ellipsis; //Konqueror Safari

-moz-text-overflow: ellipsis; //Firefox,mozilla

-webkit-text-overflow: ellipsis;  //Safari,Swift