Question

<div class="web_index">
<div style="display:block" >content 1</div>
<div style="display:none">content 2</div>
<div style="display:none">content 3</div>
</div>

i used

 var div =document.getElementsByClass("web_index").getElementsByTagName("div");

it tips me there TypeError: document.getElementsByClass is not a function.why, and how to get all the div in the web_index div?

Answer 1

Maybe

var div =document.getElementsByClassName("web_index")[0].getElementsByTagName("div");

getElementsByClassName does not exist in some Internet Explorer versions and maybe you need to create that function:

document.getElementsByClassName = function(cl) {
  var retnode = [];
  var elem = this.getElementsByTagName('*');
  for (var i = 0; i < elem.length; i++) {
    if((' ' + elem[i].className + ' ').indexOf(' ' + cl + ' ') > -1) retnode.push(elem[i]);
  }
  return retnode;
};