千秋此意
var spanElem = document.getElementsByClassName('conve-item-icon-tab')[0];
var spanElem = document.getElementsByClassName('conve J_Conve')[0].getElementsByTagName('span')[1];
var spanElem = document.querySelector('.conve-item-icon-tab');
var spanElem = document.querySelector('.conve.J_Conve ul li').children[1];
var spanElem = document.querySelectorAll('div.conve.J_Conve span')[1];