samthor

/**
 * Updates the passed dialog to retain focus and restore it when the dialog is closed. Won't
 * upgrade a dialog more than once. Supports IE11+ and is a no-op otherwise.
 * @param {!HTMLDialogElement} dialog to upgrade
 */
var registerFocusRestoreDialog = (function() {
  if (!window.WeakMap || !window.MutationObserver) {
    return function() {};
  }
  var registered = new WeakMap();

rondy

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

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Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?