I'm trying to create a test that checks the body of a webpage for a particular class using vanilla JS

currently my code looks like this

var whole = document.getElementsByTagName("body")[0];
whole.classList.contains("desiredClass");

this returns "false" on a class even though it exists in my body.

I have attempted to redefine whole as

var whole = document.body

and received the same result

Question: what is my code missing? I felt this was a pretty straightforward test, but I am certainly missing something

EDIT:

My classList function works, but was not searching for DIV classes within the body.

How do I narrow the search within the document.body to search all div classes?

I'm trying to create a test that checks the body of a webpage for a particular class using vanilla JS

currently my code looks like this

var whole = document.getElementsByTagName("body")[0];
whole.classList.contains("desiredClass");

this returns "false" on a class even though it exists in my body.

I have attempted to redefine whole as

var whole = document.body

and received the same result

Question: what is my code missing? I felt this was a pretty straightforward test, but I am certainly missing something

EDIT:

My classList function works, but was not searching for DIV classes within the body.

How do I narrow the search within the document.body to search all div classes?

• javascript
• dom

• document.querySelector('body div.desiredClass')? – melpomene Commented Oct 20, 2015 at 23:34
• Could you please also add the relevant HTML code? – Kyll Commented Oct 21, 2015 at 0:26

1 Answer 1

It's not good to findElementByTagName in this case. Using the document.body instead is much better.

Anyway, your code seems to be ok. Maybe it's browser patibility issue? Here you can see which versions of browsers supports classList property of DOM element: classList doc

You can use this solution. It is much certain.

var classes = document.body.getAttribute('class').split(' ');
var contains = classes.indexOf('desiredClass') > -1;