如何访问没有 ID 的 HTML 元素？

Question

For instance in the snippet below - how do I access the h1 element knowing the ID of parent element (header-inner div)?

<div id='header-inner'> 
   <div class='titlewrapper'> 
      <h1 class='title'> 
      Some text I want to change
      </h1> 
   </div> 
</div>

Thanks!

Answer 1

function findFirstDescendant(parent, tagname)
{
   parent = document.getElementById(parent);
   var descendants = parent.getElementsByTagName(tagname);
   if ( descendants.length )
      return descendants[0];
   return null;
}

var header = findFirstDescendant("header-inner", "h1");

Finds the element with the given ID, queries for descendants with a given tag name, returns the first one. You could also loop on descendants to filter by other criteria; if you start heading in that direction, i recommend you check out a pre-built library such as jQuery (will save you a good deal of time writing this stuff, it gets somewhat tricky).

Answer 2

If you were to use jQuery as mentioned by some posters, you can get access to the element very easily like so (though technically this would return a collection of matching elements if there were more than one H1 descendant):

var element = $('#header-inner h1');

Using a library like JQuery makes things like this trivial compared to the normal ways as mentioned in other posts. Then once you have a reference to it in a jQuery object, you have even more functions available to easily manipulate its content and appearance.

Answer 3

If you are sure that there is only one H1 element in your div:

var parent = document.getElementById('header-inner');
var element = parent.GetElementsByTagName('h1')[0];

Going through descendants,as Shog9 showed, is a good way too.

Answer 4

The simplest way of doing it with your current markup is:

document.getElementById('header-inner').getElementsByTagName('h1')[0].innerHTML = 'new text';

This assumes your H1 tag is always the first one within the 'header-inner' element.

Answer 5

To get the children nodes, use obj.childNodes , that returns a collection object.

To get the first child, use list[0] , that returns a node.

So the complete code should be:

var div = document.getElementById('header-inner');
var divTitleWrapper = div.childNodes[0];
var h1 = divTitleWrapper.childNodes[0];

If you want to iterate over all the children, comparing if they are of class “title”, you can iterate using a for loop and the className attribute.

The code should be:

var h1 = null;
var nodeList = divTitleWrapper.childNodes;
for (i =0;i < nodeList.length;i++){
    var node = nodeList[i];
    if(node.className == 'title' && node.tagName == 'H1'){
        h1 = node;
    }
}

Answer 6

Here I get the H1 elements value in a div where the H1 element which has CSS class="myheader":

var nodes = document.getElementById("mydiv")
                    .getElementsByTagName("H1");

for(i=0;i<nodes.length;i++)
{
    if(nodes.item(i).getAttribute("class") == "myheader")
        alert(nodes.item(i).innerHTML);
}      

Here is the markup:

<div id="mydiv">
   <h1 class="myheader">Hello</h1>
</div>

I would also recommend to use jQuery if you need a heavy parsing for your DOM.

Answer 7

It's been a few years since this question was asked and answered. In modern DOM, you could use querySelector :

 document.querySelector('#header-inner h1').textContent = 'Different text';

 <div id='header-inner'> <div class='titlewrapper'> <h1 class='title'> Some text I want to change </h1> </div> </div>