Sanborn Sanborn - 1 year ago 62
HTML Question

Can I access custom html tag <component> or <slot> contents

Let's say I want to create a custom html element such as:


So I create a template like this:

<div class="wrapper">

Then I attach it to the page via an HTML Element Prototype

Inside that callback I want to be able to attach listeners to the
element so I can do stuff on
etc.. It's not clear to me if there is anyway to access the video tag passed in. I can get access to the
tag but it doesn't show any child nodes. Is this possible?

I can access the video element if I just grab the whole document and get the video element but this is ugly because I want to be able to get only the video tag in the scope of the present custom element.

Answer Source

Direct way

You should access it by using querySelector on the custom element itself:

VideoContainerPrototype.createdCallback = function ()
    var video1 = this.querySelector( 'video' ) 

You don't need to pass by the Shadow DOM.

Shadow way

But if you want to get it from the Shadow root you can use the assignedNodes() method on your <slot> element (formerly getDistributedNodes() on <content>):

var video2 = this.shadowRoot.querySelector( 'slot' ).assignedNodes()[1] 

It returns an Array of Nodes that were inserted. Because in your example there's a text Node at index [0] you'll have to get the Node at [1].

Note: You can also use named slots if you want to get your <video> element at index [0].

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