Add minimum quantity, maximum quantity, and step (multiple_of) to the Cart Block and Store API

assets/js/atomic/blocks/product-elements/add-to-cart/product-types/simple.js

@@ -18,6 +18,7 @@ const Simple = () => {
 		quantity,
 		minQuantity,
 		maxQuantity,
+		multipleOf,
 		dispatchActions,
 		isDisabled,
 	} = useAddToCartFormContext();
@@ -43,6 +44,7 @@ const Simple = () => {
 				value={ quantity }
 				min={ minQuantity }
 				max={ maxQuantity }
+				step={ multipleOf }
 				disabled={ isDisabled }
 				onChange={ dispatchActions.setQuantity }
 			/>

assets/js/atomic/blocks/product-elements/add-to-cart/product-types/variable/index.js

@@ -23,6 +23,7 @@ const Variable = () => {
 		quantity,
 		minQuantity,
 		maxQuantity,
+		multipleOf,
 		dispatchActions,
 		isDisabled,
 	} = useAddToCartFormContext();
@@ -52,6 +53,7 @@ const Variable = () => {
 				value={ quantity }
 				min={ minQuantity }
 				max={ maxQuantity }
+				step={ multipleOf }
 				disabled={ isDisabled }
 				onChange={ dispatchActions.setQuantity }
 			/>

assets/js/atomic/blocks/product-elements/add-to-cart/shared/quantity-input.js

@@ -1,25 +1,71 @@
+/**
+ * External dependencies
+ */
+import { useDebouncedCallback } from 'use-debounce';
+
 /**
  * Quantity Input Component.
  *
  * @param {Object}         props          Incoming props for component
  * @param {boolean}        props.disabled Whether input is disabled or not.
  * @param {number}         props.min      Minimum value for input.
  * @param {number}         props.max      Maximum value for input.
+ * @param {number}         props.step Step attribute for input.
  * @param {number}         props.value    Value for input.
  * @param {function():any} props.onChange Function to call on input change event.
  */
-const QuantityInput = ( { disabled, min, max, value, onChange } ) => {
+const QuantityInput = ( { disabled, min, max, step = 1, value, onChange } ) => {
+	const hasMaximum = typeof max !== 'undefined';
+
+	/**
+	 * The goal of this function is to normalize what was inserted,
+	 * but after the customer has stopped typing.
+	 *
+	 * It's important to wait before normalizing or we end up with
+	 * a frustrating experience, for example, if the minimum is 2 and
+	 * the customer is trying to type "10", premature normalizing would
+	 * always kick in at "1" and turn that into 2.
+	 *
+	 * Copied from <QuantitySelector>
+	 */
+	const normalizeQuantity = useDebouncedCallback( ( initialValue ) => {
+		// We copy the starting value.
+		let newValue = initialValue;
+
+		// We check if we have a maximum value, and select the lowest between what was inserted and the maximum.
+		if ( hasMaximum ) {
+			newValue = Math.min(
+				newValue,
+				// the maximum possible value in step increments.
+				Math.floor( max / step ) * step
+			);
+		}
+
+		// Select the biggest between what's inserted, the the minimum value in steps.
+		newValue = Math.max( newValue, Math.ceil( min / step ) * step );
+
+		// We round off the value to our steps.
+		newValue = Math.floor( newValue / step ) * step;
+
+		// Only commit if the value has changed
+		if ( newValue !== initialValue ) {
+			onChange( newValue );
+		}
+	}, 300 );
+
 	return (
 		<input
 			className="wc-block-components-product-add-to-cart-quantity"
 			type="number"
 			value={ value }
 			min={ min }
 			max={ max }
+			step={ step }
 			hidden={ max === 1 }
 			disabled={ disabled }
 			onChange={ ( e ) => {
 				onChange( e.target.value );
+				normalizeQuantity( e.target.value );
 			} }
 		/>
 	);

assets/js/base/components/quantity-selector/index.tsx

@@ -4,8 +4,9 @@
 import { __, sprintf } from '@wordpress/i18n';
 import { speak } from '@wordpress/a11y';
 import classNames from 'classnames';
-import { useCallback } from '@wordpress/element';
+import { useCallback, useLayoutEffect } from '@wordpress/element';
 import { DOWN, UP } from '@wordpress/keycodes';
+import { useDebouncedCallback } from 'use-debounce';
 
 /**
  * Internal dependencies
@@ -31,6 +32,10 @@ export interface QuantitySelectorProps {
 	 * Maximum quantity
 	 */
 	maximum: number;
+	/**
+	 * Input step attribute.
+	 */
+	step?: number;
 	/**
 	 * Event handler triggered when the quantity is changed
 	 */
@@ -53,6 +58,7 @@ const QuantitySelector = ( {
 	minimum = 1,
 	maximum,
 	onChange = () => void 0,
+	step = 1,
 	itemName = '',
 	disabled,
 }: QuantitySelectorProps ): JSX.Element => {
@@ -62,8 +68,59 @@ const QuantitySelector = ( {
 	);
 
 	const hasMaximum = typeof maximum !== 'undefined';
-	const canDecrease = quantity > minimum;
-	const canIncrease = ! hasMaximum || quantity < maximum;
+	const canDecrease = quantity - step >= minimum;
+	const canIncrease = ! hasMaximum || quantity + step <= maximum;
+
+	/**
+	 * The goal of this function is to normalize what was inserted,
+	 * but after the customer has stopped typing.
+	 */
+	const normalizeQuantity = useCallback(
+		( initialValue: number ) => {
+			// We copy the starting value.
+			let value = initialValue;
+
+			// We check if we have a maximum value, and select the lowest between what was inserted and the maximum.
+			if ( hasMaximum ) {
+				value = Math.min(
+					value,
+					// the maximum possible value in step increments.
+					Math.floor( maximum / step ) * step
+				);
+			}
+
+			// Select the biggest between what's inserted, the the minimum value in steps.
+			value = Math.max( value, Math.ceil( minimum / step ) * step );
+
+			// We round off the value to our steps.
+			value = Math.floor( value / step ) * step;
+
+			// Only commit if the value has changed
+			if ( value !== initialValue ) {
+				onChange( value );
+			}
+		},
+		[ hasMaximum, maximum, minimum, onChange, step ]
+	);
+
+	/*
+	 * It's important to wait before normalizing or we end up with
+	 * a frustrating experience, for example, if the minimum is 2 and
+	 * the customer is trying to type "10", premature normalizing would
+	 * always kick in at "1" and turn that into 2.
+	 */
+	const debouncedNormalizeQuantity = useDebouncedCallback(
+		normalizeQuantity,
+		// This value is deliberately smaller than what's in useStoreCartItemQuantity so we don't end up with two requests.
+		300
+	);
+
+	/**
+	 * Normalize qty on mount before render.
+	 */
+	useLayoutEffect( () => {
+		normalizeQuantity( quantity );
+	}, [ quantity, normalizeQuantity ] );
 
 	/**
 	 * Handles keyboard up and down keys to change quantity value.
@@ -83,15 +140,15 @@ const QuantitySelector = ( {
 
 			if ( isArrowDown && canDecrease ) {
 				event.preventDefault();
-				onChange( quantity - 1 );
+				onChange( quantity - step );
 			}
 
 			if ( isArrowUp && canIncrease ) {
 				event.preventDefault();
-				onChange( quantity + 1 );
+				onChange( quantity + step );
 			}
 		},
-		[ quantity, onChange, canIncrease, canDecrease ]
+		[ quantity, onChange, canIncrease, canDecrease, step ]
 	);
 
 	return (
@@ -100,22 +157,23 @@ const QuantitySelector = ( {
 				className="wc-block-components-quantity-selector__input"
 				disabled={ disabled }
 				type="number"
-				step="1"
-				min="0"
+				step={ step }
+				min={ minimum }
+				max={ maximum }
 				value={ quantity }
 				onKeyDown={ quantityInputOnKeyDown }
 				onChange={ ( event ) => {
-					let value =
-						Number.isNaN( event.target.value ) ||
-						! event.target.value
-							? 0
-							: parseInt( event.target.value, 10 );
-					if ( hasMaximum ) {
-						value = Math.min( value, maximum );
-					}
-					value = Math.max( value, minimum );
+					// Inputs values are strings, we parse them here.
+					let value = parseInt( event.target.value, 10 );
+					// parseInt would throw NaN for anything not a number,
+					// so we revert value to the quantity value.
+					value = isNaN( value ) ? quantity : value;
+
 					if ( value !== quantity ) {
+						// we commit this value immediately.
 						onChange( value );
+						// but once the customer has stopped typing, we make sure his value is respecting the bounds (maximum value, minimum value, step value), and commit the normalized value.
+						debouncedNormalizeQuantity( value );
 					}
 				} }
 				aria-label={ sprintf(
@@ -135,7 +193,7 @@ const QuantitySelector = ( {
 				className="wc-block-components-quantity-selector__button wc-block-components-quantity-selector__button--minus"
 				disabled={ disabled || ! canDecrease }
 				onClick={ () => {
-					const newQuantity = quantity - 1;
+					const newQuantity = quantity - step;
 					onChange( newQuantity );
 					speak(
 						sprintf(
@@ -147,6 +205,7 @@ const QuantitySelector = ( {
 							newQuantity
 						)
 					);
+					normalizeQuantity( newQuantity );
 				} }
 			>
 				&#65293;
@@ -159,7 +218,7 @@ const QuantitySelector = ( {
 				disabled={ disabled || ! canIncrease }
 				className="wc-block-components-quantity-selector__button wc-block-components-quantity-selector__button--plus"
 				onClick={ () => {
-					const newQuantity = quantity + 1;
+					const newQuantity = quantity + step;
 					onChange( newQuantity );
 					speak(
 						sprintf(
@@ -171,6 +230,7 @@ const QuantitySelector = ( {
 							newQuantity
 						)
 					);
+					normalizeQuantity( newQuantity );
 				} }
 			>
 				&#65291;

assets/js/base/components/quantity-selector/style.scss

@@ -41,6 +41,7 @@
 		line-height: 1;
 		vertical-align: middle;
 		-moz-appearance: textfield;
+		font-weight: 600;
 
 		&:focus {
 			background: $gray-100;
@@ -70,11 +71,12 @@
 
 	.wc-block-components-quantity-selector__button {
 		@include reset-button;
-		@include font-size(regular);
+		@include font-size(regular, 0.9em);
 		min-width: 30px;
 		cursor: pointer;
-		color: $gray-900;
+		color: $gray-600;
 		font-style: normal;
+		font-weight: normal;
 		text-align: center;
 		text-decoration: none;
 

assets/js/base/context/providers/add-to-cart-form/form-state/constants.js

@@ -13,7 +13,7 @@ export const STATUS = {
 export const DEFAULT_STATE = {
 	status: STATUS.PRISTINE,
 	hasError: false,
-	quantity: 1,
+	quantity: 0,
 	processingResponse: null,
 	requestParams: {},
 };

assets/js/base/context/providers/add-to-cart-form/form-state/index.js

@@ -296,9 +296,11 @@ export const AddToCartFormStateContextProvider = ( {
 		productHasOptions: product.has_options || false,
 		supportsFormElements,
 		showFormElements: showFormElements && supportsFormElements,
-		quantity: addToCartFormState.quantity,
-		minQuantity: 1,
-		maxQuantity: product.quantity_limit || 99,
+		quantity:
+			addToCartFormState.quantity || product?.add_to_cart?.minimum || 1,
+		minQuantity: product?.add_to_cart?.minimum || 1,
+		maxQuantity: product?.add_to_cart?.maximum || 99,
+		multipleOf: product?.add_to_cart?.multiple_of || 1,
 		requestParams: addToCartFormState.requestParams,
 		isIdle: addToCartFormState.status === STATUS.IDLE,
 		isDisabled: addToCartFormState.status === STATUS.DISABLED,

assets/js/blocks/cart-checkout/cart/cart-line-items-table/cart-line-item-row.tsx

@@ -70,7 +70,13 @@ const CartLineItemRow = forwardRef< HTMLTableRowElement, CartLineItemRowProps >(
 			description: fullDescription = '',
 			low_stock_remaining: lowStockRemaining = null,
 			show_backorder_badge: showBackorderBadge = false,
-			quantity_limit: quantityLimit = 99,
+			quantity_limits: quantityLimits = {
+				minimum: 1,
+				maximum: 99,
+				multiple_of: 1,
+				editable: true,
+			},
+			sold_individually: soldIndividually = false,
 			permalink = '',
 			images = [],
 			variation = [],
@@ -278,19 +284,26 @@ const CartLineItemRow = forwardRef< HTMLTableRowElement, CartLineItemRowProps >(
 					/>
 
 					<div className="wc-block-cart-item__quantity">
-						<QuantitySelector
-							disabled={ isPendingDelete }
-							quantity={ quantity }
-							maximum={ quantityLimit }
-							onChange={ ( newQuantity ) => {
-								setItemQuantity( newQuantity );
-								dispatchStoreEvent( 'cart-set-item-quantity', {
-									product: lineItem,
-									quantity: newQuantity,
-								} );
-							} }
-							itemName={ name }
-						/>
+						{ ! soldIndividually && !! quantityLimits.editable && (
+							<QuantitySelector
+								disabled={ isPendingDelete }
+								quantity={ quantity }
+								minimum={ quantityLimits.minimum }
+								maximum={ quantityLimits.maximum }
+								step={ quantityLimits.multiple_of }
+								onChange={ ( newQuantity ) => {
+									setItemQuantity( newQuantity );
+									dispatchStoreEvent(
+										'cart-set-item-quantity',
+										{
+											product: lineItem,
+											quantity: newQuantity,
+										}
+									);
+								} }
+								itemName={ name }
+							/>
+						) }
 						<button
 							className="wc-block-cart-item__remove-link"
 							onClick={ () => {