WooCommerce Quantity Before Add to Cart and Product Update

add-to-cart.php

<?php
/**
 * Custom Loop Add to Cart.
 *
 * Template with quantity and ajax.
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly.

global $product;
?>

<?php if ( ! $product->is_in_stock() ) : ?>

 <a href="<?php echo apply_filters( 'out_of_stock_add_to_cart_url', get_permalink( $product->id ) ); ?>" class="button"><?php echo apply_filters( 'out_of_stock_add_to_cart_text', __( 'Read More', 'woocommerce' ) ); ?></a>

<?php else : ?>

 <?php
 $link = array(
 'url' => '',
 'label' => '',
 'class' => ''
 );

 switch ( $product->product_type ) {
 case "variable" :
 $link['url'] = apply_filters( 'variable_add_to_cart_url', get_permalink( $product->id ) );
 $link['label'] = apply_filters( 'variable_add_to_cart_text', __( 'Select options', 'woocommerce' ) );
 break;
 case "grouped" :
 $link['url'] = apply_filters( 'grouped_add_to_cart_url', get_permalink( $product->id ) );
 $link['label'] = apply_filters( 'grouped_add_to_cart_text', __( 'View options', 'woocommerce' ) );
 break;
 case "external" :
 $link['url'] = apply_filters( 'external_add_to_cart_url', get_permalink( $product->id ) );
 $link['label'] = apply_filters( 'external_add_to_cart_text', __( 'Read More', 'woocommerce' ) );
 break;
 default :
 if ( $product->is_purchasable() ) {
 $link['url'] = apply_filters( 'add_to_cart_url', esc_url( $product->add_to_cart_url() ) );
 $link['label'] = apply_filters( 'add_to_cart_text', __( 'Add to cart', 'woocommerce' ) );
 $link['class'] = apply_filters( 'add_to_cart_class', 'add_to_cart_button' );
 } else {
 $link['url'] = apply_filters( 'not_purchasable_url', get_permalink( $product->id ) );
 $link['label'] = apply_filters( 'not_purchasable_text', __( 'Read More', 'woocommerce' ) );
 }
 break;
 }

 // If there is a simple product.
 if ( $product->product_type == 'simple' ) {
 ?>
 <form action="<?php echo esc_url( $product->add_to_cart_url() ); ?>" class="cart" method="post" enctype="multipart/form-data">
 <?php
 // Displays the quantity box.
 woocommerce_quantity_input();

 // Display the submit button.
 echo sprintf( '<button type="submit" data-product_id="%s" data-product_sku="%s" data-quantity="1" class="%s button product_type_simple">%s</button>', esc_attr( $product->id ), esc_attr( $product->get_sku() ), esc_attr( $link['class'] ), esc_html( $link['label'] ) );
 ?>
 </form>
 <?php
 } else {
 echo apply_filters( 'woocommerce_loop_add_to_cart_link', sprintf('<a href="%s" rel="nofollow" data-product_id="%s" data-product_sku="%s" class="%s button product_type_%s">%s</a>', esc_url( $link['url'] ), esc_attr( $product->id ), esc_attr( $product->get_sku() ), esc_attr( $link['class'] ), esc_attr( $product->product_type ), esc_html( $link['label'] ) ), $product, $link );
 }

 ?>

<?php endif; ?>

functions.php

function insertcart_wc_loop_add_to_cart_scripts() {
 if ( is_shop() || is_product_category() || is_product_tag() || is_product() ) : ?>

<script>
 jQuery( document ).ready( function( $ ) {
 $( document ).on( 'change', '.quantity .qty', function() {
 $( this ).parent( '.quantity' ).next( '.add_to_cart_button' ).attr( 'data-quantity', $( this ).val() );
 });
 });
</script>

 <?php endif;
}

add_action( 'wp_footer', 'insertcart_wc_loop_add_to_cart_scripts' );

http://www.insertcart.com/woocommerce-quantity-before-add-to-cart-and-product-update/