Set style using pure JavaScript [duplicate]

I want to set body's background without jQuery.

jquery : $('body').css('background','red'); 

Why won't this work in pure JavaScript?

document.getElementsByTagName('body').style['background'] = 'red'; 

3 Answers

document.getElementsByTagName('div')[0].style.backgroundColor = 'RED';

<div>sample</div>

There are many ways you can set the background color. But getElementsByTagName does not return a single object. It's a collection of objects

document.body.style.backgroundColor = "green"; // JavaScript document.getElementsByTagName("body")[0].style.backgroundColor = "green"; // Another one 

See the demo

getElementsByTagName does not return a single element, but instead a collection.

Try this:

document.getElementsByTagName('body')[0].style.backgroundColor = 'red';