输入:className:类名;root:父节点,在此节点下查找,string/node; tagName:找某一类标签
function getElementsByClassName(className,root,tagName){ if(root){ root=typeof root=="string"?document.getElementById(root):root; }else{ root=document.body; } tagName=tagName||"*"; var els=root.getElementsByTagName(tagName),arr=[]; for(var i=0;i<els.length;i++){ var classArray=els[i].className.split(" "); for(var j=0;j<classArray.length;j++){ if(classArray[j]==className){ arr.push(els[i]); break; } } } return arr; }