Product archives: Simple products separate plus and minus quantity buttons

add_filter(
	'woocommerce_loop_add_to_cart_link',
	'quantity_inputs_for_woocommerce_loop_add_to_cart_link',
	function( $html, $product ) {

	if(
		$product && $product->is_type( 'simple' )
		&& $product->is_purchasable()
		&& $product->is_in_stock()
		&& ! $product->is_sold_individually()
	) {
		$html = sprintf(
			'
				<form action="%s" class="cart" method="post" enctype="multipart/form-data">
					<div class="quantity_buttons">
						<input type="button" value="-" class="minus" />
						%s
						<input type="button" value="+" class="plus" />
					</div>
					<p><button type="submit" class="button alt">%s</button></p>
				</form>
			',
			esc_url( $product->add_to_cart_url() ),
			woocommerce_quantity_input( [ 'min_value' => 1 ], $product, false ),
			esc_html( $product->add_to_cart_text() )
		);
	}

	return $html;

}, 10, 2 );

add_action( 'wp_enqueue_scripts', function() {

	wp_enqueue_script( 'jquery' );

	wp_add_inline_script( 'jquery', '

		jQuery( document ).ready( function( $ ) {

			String.prototype.getDecimals || ( String.prototype.getDecimals = function() {
				var a = this, b = ( "" + a ).match( /(?:\.(\d+))?(?:[eE]([+-]?\d+))?$/ );
				return b ? Math.max( 0, ( b[1] ? b[1].length : 0 ) - ( b[2] ? +b[2] : 0 ) ) : 0
			} ), jQuery( document ).on( "click", ".plus, .minus", function() {

				var a = jQuery( this ).closest( ".quantity_buttons" ).find( ".qty" ),
				b = parseFloat( a.val() ),
				c = parseFloat( a.attr( "max" ) ),
				d = parseFloat( a.attr( "min" ) ),
				e = a.attr( "step" );
				b && "" !== b && "NaN" !== b || ( b = 0 ),
					"" !== c && "NaN" !== c || ( c = "" ),
					"" !== d && "NaN" !== d || ( d = 0 ),
					"any" !== e && "" !== e
						&& void 0 !== e
						&& "NaN" !== parseFloat( e )
						|| ( e = 1 ),
					jQuery( this ).is( ".plus" ) ? c && b >= c ? a.val( c )
						: a.val( ( b + parseFloat( e ) ).toFixed( e.getDecimals() ) )
						: d && b <= d
							? a.val( d )
							: b > 0 && a.val( ( b - parseFloat( e ) )
								.toFixed( e.getDecimals() ) ),
					a.trigger( "change" );

			} );

		} );

	', 'after' );

} );