javascript通过classname获取子元素

function getElementsByClassName(objparent,classna) {

3 var classElements = [],allElements = objparent.getElementsByTagName("div");

4 for (var i=0; i< allElements.length; i++ )

5 {

6 if (allElements[i].className == classna ) {

7 classElements[classElements.length] = allElements[i];

8 }

9 }

10 return classElements;

11 }

12 function showDiv(ID){

13

14 var onlines = document.getElementById("online");

15 var childelements = getElementsByClassName(onlines,"online");

16 for (var i = 0; i < childelements.length; i++) {

17 var e = childelements[i];

18 e.style.display = "none";

19 }

20 document.getElementById("online" + ID).style.display = "block";

21 }

22