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JavaScript JavaScript and the DOM (Retiring) Getting a Handle on the DOM Selecting Multiple Elements

Posted by Steve Fau
Steve Fau
5,622 Points

I've used getElementById('rainbow').getElementsByTagName('li') and it worked. Why?

I've successfully used:

getElementById('rainbow').getElementsByTagName('li')

But I thought it shouldn't work.

I thought .getElement or .getElements is a DOM method and therefore should be applicable to the document object only. Or am I wrong?

John Johnson
John Johnson
11,789 Points

DOM methods are applicable to HTML Elements, or more accurately, objects within the DOM.

In your case, document.getElementById('rainbow') is an object with the ID of rainbow. Since it is an object, the .getElementsByTagName() method still works on it. So, document.getElementById('rainbow').getElementsByTagName('li') will successfully return an array of the <li> elements under #rainbow.

However, it is usually best practice to assign #rainbow to a variable and use .getElementsByTagName() on the variable.

1 Answer

Michael Kobela
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Michael Kobela
Full Stack JavaScript Techdegree Graduate 19,570 Points
Michael Kobela
.a{fill-rule:evenodd;}techdegree seal-36
Michael Kobela
Full Stack JavaScript Techdegree Graduate 19,570 Points

Let's rewrite this to make it easier to follow::

let ulElement = document.getElementById('rainbow');
let liElementList = ulElement.getElementsByTagName('li') ;

The first call is looking for a ul element within the document. The second is looking for a list of li elements within the ul element. So the calls are not all based off the document. It's referred to as object chaining when the code is all together:

getElementById('rainbow').getElementsByTagName('li'); The first call returns the ulElement, the second call is based object returned from the first call.

msdsmd sm,dfsadf
msdsmd sm,dfsadf
1,124 Points

Please someone help me with JavaScript to apply a ripple effect .

``

<!DOCTYPE html> <html> <head> <title>Page Title</title> <style> body > div{position:relative; height:256px; overflow:hidden; width:256px; border:3px solid #000; }

@keyframes move{ 0%{ transform:scale(0);opacity:1; } 100%{ opacity:0;transform:scale(21); } }

.red{ height: 100%; opacity:0; cursor:pointer; background: rgba(0, 0, 0, 1); width: 100%; pointer-events:none; position: absolute; }

.blue{animation:2.5s move; }

::before,*::after{ margin:0; padding:0; box-sizing:border-box; }

</style> </head> <body> <div tabindex="0"> <div class="red"></div> </div> <script> const parent = document.querySelector('div'); const child = parent.children[0] parent.addEventListener('click',function(e){

if(e.target.tagName === 'DIV'){ child.classList.add('blue'); child.style.left = e.clientX + "px"; child.style.top = e.clientY + "px"; }

}) </script> </body> </html>

``