el.closest not supported in IE11

Do you want to request a feature or report a bug?

Bug

What’s the current behavior?

el.closest is called from Content.isInEditor (among a number of places). It seems like this method is not supported in IE11, and it throws an error.

What’s the expected behavior?

The error should not occur. One possible solution (based on mdn web docs) is just to polyfill the method.

[Opty1712]

Two polyfills for IE11, that made Slate working in IE 11

/**
 * closest
 */
(function () {
  if (!Element.prototype.closest) {
    Element.prototype.closest = function (css) {
      var node = this;

      while (node) {
        if (node.matches(css)) return node;
        else node = node.parentElement;
      }

      return null;
    };
  }
})();

/**
 * matches
 */
(function () {
  if (!Element.prototype.matches) {
    Element.prototype.matches =
      Element.prototype.matchesSelector ||
      Element.prototype.webkitMatchesSelector ||
      Element.prototype.mozMatchesSelector ||
      Element.prototype.msMatchesSelector;
  }
})();

[ianstormtaylor]

Feel free to submit a pull request mentioning that older browsers will need to use polyfills for things like el.closest.

I realize that IE is the latest Internet Explorer, but seeing as it’s superseded by Edge, and doesn’t have tons of the functionality that is considered baseline these days, it’s not something that we’re going to support without polyfills. Otherwise every single library starts re-bundling the same polyfills over and over and everyone else suffers from bloat.