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Discussion on: Learn basic Web Components

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Danny Engelman • Edited

See what code newcomers have to dig through (unless they don't RTFM) in the attachShadow MDN documentation:

If you understand "// Always call super first in constructor" is incorrect
you can write that 33 lines constructor (most likely) without any comments:

constructor() {

  let span = document.createElement('span');

  function countWords() {
    let node = this.parentNode;
    let text = node.innerText || node.textContent;
    let count = text.trim().split(/\s+/g).length;
    span.innerText = 'Words: ' + count;

   .attachShadow({mode: 'open'})
   .append( span );

  setInterval(()=> countWords() , 200);
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If you want to score W3C points; feel free to update that MDN article.

I did some MDN updates; then concluded there is way more effect adding comments to Web Component blogposts.
And I recently published my first post explaining Web Components are about semantic HTML (IMHO)

And ... there is more wrong in that MDN Count Words example..

  • this.parentNode DOM access should be done in the connectedCallback, as the DOM might not even exist when the constructor runs

  • <p is="word-count"></p> Will never work in Safari, because Apple only implemented Autonomous Elements and (for the past 5 years) has strong arguments to not implement Customized Built-In Elements

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