More changes.

Adding some minor changes.  Maintainability improvements, and cleaning
up unused code.  Fix an error condition where the list of blocks is
empty. Fix arrow key behavior in search field so that left and right
arrow keys can move the cursor properly.

editor/components/inserter/index.js

@@ -12,7 +12,6 @@ import IconButton from 'components/icon-button';
 class Inserter extends wp.element.Component {
 	constructor() {
 		super( ...arguments );
-		this.nodes = {};
 		this.toggle = this.toggle.bind( this );
 		this.close = this.close.bind( this );
 		this.state = {

editor/components/inserter/menu.js

@@ -47,13 +47,19 @@ class InserterMenu extends wp.element.Component {
 
 	isNextKeydown( keydown ) {
 		return keydown.code === 'ArrowDown'
-			|| keydown.code === 'ArrowRight'
 			|| ( keydown.code === 'Tab' && keydown.shiftKey === false );
 	}
 
+	isArrowRight( keydown ) {
+		return keydown.code === 'ArrowRight';
+	}
+
+	isArrowLeft( keydown ) {
+		return keydown.code === 'ArrowLeft';
+	}
+
 	isPreviousKeydown( keydown ) {
 		return keydown.code === 'ArrowUp'
-			|| keydown.code === 'ArrowLeft'
 			|| ( keydown.code === 'Tab' && keydown.shiftKey === true );
 	}
 
@@ -115,10 +121,10 @@ class InserterMenu extends wp.element.Component {
 
 	findNext( currentBlock, blockTypes ) {
 		/**
-		 * 'search' or null are the values that will trigger iterating back to
+		 * null is the value that will trigger iterating back to
 		 * the top of the list of block types.
 		 */
-		if ( null === currentBlock || 'search' === currentBlock ) {
+		if ( null === currentBlock ) {
 			return blockTypes[ 0 ].slug;
 		}
 
@@ -179,14 +185,15 @@ class InserterMenu extends wp.element.Component {
 			this.getVisibleBlocks,
 			this.sortBlocksByCategory,
 		)( component.blockTypes );
-		const currentBlock = component.state.currentFocus;
 
-		let nextBlock = this.findNext( currentBlock, sortedByCategory );
-
-		if ( nextBlock === null ) {
-			nextBlock = 'search';
+		// If the block list is empty return early.
+		if ( ! sortedByCategory.length ) {
+			return;
 		}
 
+		const currentBlock = component.state.currentFocus;
+
+		const nextBlock = this.findNext( currentBlock, sortedByCategory );
 		this.changeMenuSelection( nextBlock );
 	}
 
@@ -197,12 +204,12 @@ class InserterMenu extends wp.element.Component {
 		)( component.blockTypes );
 		const currentBlock = component.state.currentFocus;
 
-		let nextBlock = this.findPrevious( currentBlock, sortedByCategory );
-
-		if ( nextBlock === null ) {
-			nextBlock = 'search';
+		// If the block list is empty return early.
+		if ( ! sortedByCategory.length ) {
+			return;
 		}
 
+		const nextBlock = this.findPrevious( currentBlock, sortedByCategory );
 		this.changeMenuSelection( nextBlock );
 	}
 
@@ -217,13 +224,35 @@ class InserterMenu extends wp.element.Component {
 			this.focusPrevious( this );
 		}
 
+		/**
+		 * Left and right arrow keys need to be handled seperately so that
+		 * default cursor behavior can be handled in the search field.
+		 */
+		if ( this.isArrowRight( keydown ) ) {
+			if ( this.state.currentFocus === 'search' ) {
+				return;
+			}
+			this.focusNext( this );
+		}
+
+		if ( this.isArrowLeft( keydown ) ) {
+			if ( this.state.currentFocus === 'search' ) {
+				return;
+			}
+			this.focusPrevious( this );
+		}
+
 		if ( this.isEscapeKey( keydown ) ) {
 			keydown.preventDefault();
 			this.props.closeMenu();
 		}
 	}
 
 	changeMenuSelection( refName ) {
+		if ( refName === null ) {
+			refName = 'search';
+		}
+
 		this.setState( {
 			currentFocus: refName
 		} );
@@ -291,6 +320,7 @@ class InserterMenu extends wp.element.Component {
 					onChange={ this.filter }
 					onClick={ this.setSearchFocus }
 					ref={ this.bindReferenceNode( 'search' ) }
+					tabIndex="-1"
 				/>
 			</div>
 		);