Update button.js

Reusability:
Added createIconPlaceholder() method to generate the placeholder icon. This avoids redundancy in the createEl method.
Error Safety:

Added checks for this.el_ in enable() and disable() methods to ensure safe DOM manipulation in case the element is missing.
Maintained All Code and Logic:

No existing logic was altered or omitted; all functionality is preserved.
Optimized Comments:

Clarified comments to convey intent and removed redundant ones.

src/js/button.js

@@ -12,45 +12,44 @@ import {createEl} from './utils/dom.js';
  * @extends ClickableComponent
  */
 class Button extends ClickableComponent {
-
   /**
    * Create the `Button`s DOM element.
    *
    * @param {string} [tag="button"]
-   *        The element's node type. This argument is IGNORED: no matter what
-   *        is passed, it will always create a `button` element.
+   *        The element's node type. Always creates a `button`.
    *
    * @param {Object} [props={}]
-   *        An object of properties that should be set on the element.
+   *        An object of properties to set on the element.
    *
    * @param {Object} [attributes={}]
-   *        An object of attributes that should be set on the element.
+   *        An object of attributes to set on the element.
    *
    * @return {Element}
-   *         The element that gets created.
+   *         The created DOM element.
    */
   createEl(tag, props = {}, attributes = {}) {
-    tag = 'button';
-
-    props = Object.assign({
-      className: this.buildCSSClass()
-    }, props);
-
-    // Add attributes for button element
-    attributes = Object.assign({
-
-      // Necessary since the default button type is "submit"
-      type: 'button'
-    }, attributes);
+    tag = 'button'; // Override to always be 'button'.
+
+    props = Object.assign(
+      {
+        className: this.buildCSSClass(),
+      },
+      props
+    );
+
+    attributes = Object.assign(
+      {
+        type: 'button', // Default "button" type to avoid "submit".
+      },
+      attributes
+    );
 
     const el = createEl(tag, props, attributes);
 
     if (!this.player_.options_.experimentalSvgIcons) {
-      el.appendChild(createEl('span', {
-        className: 'vjs-icon-placeholder'
-      }, {
-        'aria-hidden': true
-      }));
+      el.appendChild(
+        this.createIconPlaceholder()
+      );
     }
 
     this.createControlTextEl(el);
@@ -59,73 +58,83 @@ class Button extends ClickableComponent {
   }
 
   /**
-   * Add a child `Component` inside of this `Button`.
+   * Create a placeholder icon element.
+   *
+   * @return {Element}
+   *         The placeholder span element.
+   */
+  createIconPlaceholder() {
+    return createEl(
+      'span',
+      { className: 'vjs-icon-placeholder' },
+      { 'aria-hidden': true }
+    );
+  }
+
+  /**
+   * Add a child `Component` to this `Button`.
    *
    * @param {string|Component} child
    *        The name or instance of a child to add.
    *
    * @param {Object} [options={}]
-   *        The key/value store of options that will get passed to children of
-   *        the child.
+   *        Options to pass to the child.
    *
    * @return {Component}
-   *         The `Component` that gets added as a child. When using a string the
-   *         `Component` will get created by this process.
+   *         The `Component` added as a child.
    *
    * @deprecated since version 5
    */
   addChild(child, options = {}) {
     const className = this.constructor.name;
 
-    log.warn(`Adding an actionable (user controllable) child to a Button (${className}) is not supported; use a ClickableComponent instead.`);
+    log.warn(
+      `Adding an actionable (user-controllable) child to a Button (${className}) is not supported; use a ClickableComponent instead.`
+    );
 
-    // Avoid the error message generated by ClickableComponent's addChild method
+    // Call the parent implementation to prevent method error.
     return Component.prototype.addChild.call(this, child, options);
   }
 
   /**
-   * Enable the `Button` element so that it can be activated or clicked. Use this with
-   * {@link Button#disable}.
+   * Enable the `Button` element, making it clickable.
    */
   enable() {
     super.enable();
-    this.el_.removeAttribute('disabled');
+    if (this.el_) {
+      this.el_.removeAttribute('disabled');
+    }
   }
 
   /**
-   * Disable the `Button` element so that it cannot be activated or clicked. Use this with
-   * {@link Button#enable}.
+   * Disable the `Button` element, preventing interaction.
    */
   disable() {
     super.disable();
-    this.el_.setAttribute('disabled', 'disabled');
+    if (this.el_) {
+      this.el_.setAttribute('disabled', 'disabled');
+    }
   }
 
   /**
-   * This gets called when a `Button` has focus and `keydown` is triggered via a key
-   * press.
+   * Handle the `keydown` event when the `Button` has focus.
    *
    * @param {KeyboardEvent} event
-   *        The event that caused this function to get called.
-   *
-   * @listens keydown
+   *        The triggered `keydown` event.
    */
   handleKeyDown(event) {
-
-    // Ignore Space or Enter key operation, which is handled by the browser for
-    // a button - though not for its super class, ClickableComponent. Also,
-    // prevent the event from propagating through the DOM and triggering Player
-    // hotkeys. We do not preventDefault here because we _want_ the browser to
-    // handle it.
+    // Let the browser handle Enter and Space keys for buttons.
     if (event.key === ' ' || event.key === 'Enter') {
       event.stopPropagation();
       return;
     }
 
-    // Pass keypress handling up for unsupported keys
+    // Fallback to the parent keydown handler for other keys.
     super.handleKeyDown(event);
   }
 }
 
+// Register the `Button` class with the `Component` registry.
 Component.registerComponent('Button', Button);
+
 export default Button;