Webcomponents.js Issue On Ie And Firefox

I try to make a simple web component. For browser compatibility, I use the NPM package webcomponents.js (version 0.7.23). I run my little code with Polyserve. My code is on Github:

Solution 1:

In your main file index.html you are loading the webcomponents-lite.js script, which doesn't include the Shadow DOM polyfill.

Instead, try to load webcomponents.js.

---

For Shadow DOM v1 attachShadow(), you should use instead the ShadyDOM polyfill. In this case you should use webcomponents-lite.js otherwise there will be a conflict with createShadowRoot() polyfill.

<scriptsrc="./node_modules/webcomponents.js/webcomponents-lite.js"></script><scriptsrc="shadydom.min.js"></script><script>if (!Array.from) {
    Array.from = function (object) {
        'use strict';
        return [].slice.call(object);
    };
}
</script>