Rewrite Button to Typescript (#2984)

* Rename Button file

* Convert to TS

* Add debug warning helper

Fires `console.warn`, but only when the forum is in debug mode. Can help to inform extension developers of possible issues with their JS code.

* Simplify button content template

* Rewrite Button component

- Prefer `aria-label` over `title`
- Don't duplicate button content to `title` attribute
- Warn in debug mode if button has no accessible content
- Use modern JS/TS syntax (`||=`, spread, etc)

* Update to work with new Button component

* Update warning

Co-authored-by: Matt Kilgore <tankerkiller125@gmail.com>

* Fire warning in `oncreate`

* Format

* Make Button have extensible Attributes type via generics

* Update args type

* Update js/src/common/components/Button.tsx

Co-authored-by: Matt Kilgore <tankerkiller125@gmail.com>
Co-authored-by: David Sevilla Martin <me@datitisev.me>
Co-authored-by: Alexander Skvortsov <sasha.skvortsov109@gmail.com>

js/src/common/components/Button.tsx

@@ -0,0 +1,130 @@
+import type Mithril from 'mithril';
+import Component, { ComponentAttrs } from '../Component';
+import fireDebugWarning from '../helpers/fireDebugWarning';
+import icon from '../helpers/icon';
+import classList from '../utils/classList';
+import extractText from '../utils/extractText';
+import LoadingIndicator from './LoadingIndicator';
+
+export interface IButtonAttrs extends ComponentAttrs {
+  /**
+   * Class(es) of an optional icon to be rendered within the button.
+   *
+   * If provided, the button will gain a `has-icon` class.
+   */
+  icon?: string;
+  /**
+   * Disables button from user input.
+   *
+   * Default: `false`
+   */
+  disabled?: boolean;
+  /**
+   * Show a loading spinner within the button.
+   *
+   * If `true`, also disables the button.
+   *
+   * Default: `false`
+   */
+  loading?: boolean;
+  /**
+   * **DEPRECATED:** Please use the `aria-label` attribute instead. For tooltips, use
+   * the `<Tooltip>` component.
+   *
+   * Accessible text for the button. This should always be present if the button only
+   * contains an icon.
+   *
+   * The textual content of this attribute is passed to the DOM element as `aria-label`.
+   *
+   * @deprecated
+   */
+  title?: string | Mithril.ChildArray;
+  /**
+   * Accessible text for the button. This should always be present if the button only
+   * contains an icon.
+   *
+   * The textual content of this attribute is passed to the DOM element as `aria-label`.
+   */
+  'aria-label'?: string | Mithril.ChildArray;
+  /**
+   * Button type.
+   *
+   * Default: `"button"`
+   *
+   * @see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#attr-type
+   */
+  type?: string;
+}
+
+/**
+ * The `Button` component defines an element which, when clicked, performs an
+ * action.
+ *
+ * Other attrs will be assigned as attributes on the `<button>` element.
+ *
+ * Note that a Button has no default class names. This is because a Button can
+ * be used to represent any generic clickable control, like a menu item. Common
+ * styles can be applied by providing `className="Button"` to the Button component.
+ */
+export default class Button<CustomAttrs extends IButtonAttrs = IButtonAttrs> extends Component<CustomAttrs> {
+  view(vnode: Mithril.Vnode<IButtonAttrs, never>) {
+    let { type, title, 'aria-label': ariaLabel, icon: iconName, disabled, loading, className, class: _class, ...attrs } = this.attrs;
+
+    // If no `type` attr provided, set to "button"
+    type ||= 'button';
+
+    // Use `title` attribute as `aria-label` if none provided
+    ariaLabel ||= title;
+
+    // If given a translation object, extract the text.
+    if (typeof ariaLabel === 'object') {
+      ariaLabel = extractText(ariaLabel);
+    }
+
+    if (disabled || loading) {
+      delete attrs.onclick;
+    }
+
+    className = classList(_class, className, {
+      hasIcon: iconName,
+      disabled: disabled || loading,
+      loading: loading,
+    });
+
+    const buttonAttrs = {
+      disabled,
+      className,
+      type,
+      'aria-label': ariaLabel,
+      ...attrs,
+    };
+
+    return <button {...buttonAttrs}>{this.getButtonContent(vnode.children)}</button>;
+  }
+
+  oncreate(vnode: Mithril.VnodeDOM<IButtonAttrs, this>) {
+    super.oncreate(vnode);
+
+    const { 'aria-label': ariaLabel } = this.attrs;
+
+    if (!ariaLabel && !extractText(vnode.children) && !this.element?.getAttribute?.('aria-label')) {
+      fireDebugWarning(
+        '[Flarum Accessibility Warning] Button has no content and no accessible label. This means that screen-readers will not be able to interpret its meaning and just read "Button". Consider providing accessible text via the `aria-label` attribute. https://web.dev/button-name',
+        this.element
+      );
+    }
+  }
+
+  /**
+   * Get the template for the button's content.
+   */
+  protected getButtonContent(children: Mithril.Children): Mithril.ChildArray {
+    const iconName = this.attrs.icon;
+
+    return [
+      iconName && icon(iconName, { className: 'Button-icon' }),
+      children && <span className="Button-label">{children}</span>,
+      this.attrs.loading && <LoadingIndicator size="small" display="inline" />,
+    ];
+  }
+}

js/src/common/components/TextEditorButton.js

@@ -1,24 +1,27 @@
+import extractText from '../utils/extractText';
 import Button from './Button';
 import Tooltip from './Tooltip';
 
 /**
  * The `TextEditorButton` component displays a button suitable for the text
  * editor toolbar.
+ *
+ * Automatically creates tooltips using the Tooltip component and provided text.
+ *
+ * ## Attrs
+ * - `title` - Tooltip for the button
  */
 export default class TextEditorButton extends Button {
   view(vnode) {
     const originalView = super.view(vnode);
 
-    // Steal tooltip label from the Button superclass
-    const tooltipText = originalView.attrs.title;
-    delete originalView.attrs.title;
-
-    return <Tooltip text={tooltipText}>{originalView}</Tooltip>;
+    return <Tooltip text={this.attrs.tooltipText || extractText(vnode.children)}>{originalView}</Tooltip>;
   }
 
   static initAttrs(attrs) {
     super.initAttrs(attrs);
 
     attrs.className = attrs.className || 'Button Button--icon Button--link';
+    attrs.tooltipText = attrs.title;
   }
 }

js/src/common/helpers/fireDebugWarning.ts

@@ -0,0 +1,16 @@
+/**
+ * Calls `console.warn` with the provided arguments, but only if the forum is in debug mode.
+ *
+ * This function is intended to provide warnings to extension developers about issues with
+ * their extensions that may not be easily noticed when testing, such as accessibility
+ * issues.
+ *
+ * These warnings should be hidden on production forums to ensure webmasters are not
+ * inundated with do-gooders telling them they have an issue when it isn't something they
+ * can fix.
+ */
+export default function fireDebugWarning(...args: Parameters<typeof console.warn>): void {
+  if (!app.forum.attribute('debug')) return;
+
+  console.warn(...args);
+}