fix(Modal): Focus primary actionable button on modal opening

src/components/Button/Button.js

@@ -37,14 +37,24 @@ const Button = ({
   ) : null;
 
   const button = (
-    <button {...other} {...commonProps} disabled={disabled} type={type}>
+    <button
+      {...other}
+      {...commonProps}
+      disabled={disabled}
+      type={type}
+      ref={other.inputref}>
       {children}
       {buttonImage}
     </button>
   );
 
   const anchor = (
-    <a {...other} {...commonProps} href={href} role="button">
+    <a
+      {...other}
+      {...commonProps}
+      href={href}
+      role="button"
+      ref={other.inputref}>
       {children}
       {buttonImage}
     </a>

src/components/Modal/Modal.js

@@ -37,6 +37,8 @@ export default class Modal extends Component {
     modalLabel: '',
   };
 
+  button = React.createRef();
+
   handleKeyDown = evt => {
     if (evt.which === 27) {
       this.props.onRequestClose();
@@ -52,6 +54,31 @@ export default class Modal extends Component {
     }
   };
 
+  componentDidUpdate(prevProps) {
+    if (!prevProps.open && this.props.open) {
+      this.beingOpen = true;
+    } else if (prevProps.open && !this.props.open) {
+      this.beingOpen = false;
+    }
+  }
+
+  focusButton = () => {
+    if (this.button) {
+      this.button.current.focus();
+    }
+  };
+
+  handleTransitionEnd = () => {
+    if (
+      this.outerModal.offsetWidth &&
+      this.outerModal.offsetHeight &&
+      this.beingOpen
+    ) {
+      this.focusButton();
+      this.beingOpen = false;
+    }
+  };
+
   render() {
     const {
       modalHeading,
@@ -86,7 +113,8 @@ export default class Modal extends Component {
       <button
         className="bx--modal-close"
         type="button"
-        onClick={onRequestClose}>
+        onClick={onRequestClose}
+        ref={this.button}>
         <Icon
           name="close"
           className="bx--modal-close__icon"
@@ -123,7 +151,8 @@ export default class Modal extends Component {
               <Button
                 kind={danger ? 'danger--primary' : 'primary'}
                 disabled={primaryButtonDisabled}
-                onClick={onRequestSubmit}>
+                onClick={onRequestSubmit}
+                inputref={this.button}>
                 {primaryButtonText}
               </Button>
             </div>
@@ -139,7 +168,11 @@ export default class Modal extends Component {
         onClick={this.handleClick}
         className={modalClasses}
         role="presentation"
-        tabIndex={-1}>
+        tabIndex={-1}
+        onTransitionEnd={this.props.open ? this.handleTransitionEnd : undefined}
+        ref={outerModal => {
+          this.outerModal = outerModal;
+        }}>
         {modalBody}
       </div>
     );

src/components/ModalWrapper/__snapshots__/ModalWrapper-test.js.snap

@@ -149,6 +149,18 @@ exports[`ModalWrapper should render 1`] = `
               <Button
                 disabled={false}
                 iconDescription="Provide icon description if icon is used"
+                inputref={
+                  Object {
+                    "current": <button
+                      class="bx--btn bx--btn--primary"
+                      inputref="[object Object]"
+                      tabindex="0"
+                      type="button"
+                    >
+                      Save
+                    </button>,
+                  }
+                }
                 kind="primary"
                 onClick={[Function]}
                 small={false}
@@ -158,6 +170,18 @@ exports[`ModalWrapper should render 1`] = `
                 <button
                   className="bx--btn bx--btn--primary"
                   disabled={false}
+                  inputref={
+                    Object {
+                      "current": <button
+                        class="bx--btn bx--btn--primary"
+                        inputref="[object Object]"
+                        tabindex="0"
+                        type="button"
+                      >
+                        Save
+                      </button>,
+                    }
+                  }
                   onClick={[Function]}
                   tabIndex={0}
                   type="button"