Fixing Cart Widget showing the incorrect item when using WPML with WooCommerce, by forcing cart widget to refresh on every page load.

cart-cache-breaker.php

	/** Break html5 cart caching */
	add_action('wp_enqueue_scripts', 'cartcache_enqueue_scripts', 100);

	function cartcache_enqueue_scripts()
	{
		wp_deregister_script('wc-cart-fragments');
		wp_enqueue_script( 'wc-cart-fragments', get_template_directory_uri()  . '/cart-fragments.js', array( 'jquery', 'jquery-cookie' ), '1.0', true );
	}

cart-fragments.js

/** Modified cart-fragments.js script to break HTML5 fragment caching. Useful with WPML when switching languages **/
jQuery(document).ready(function($) {

    /** Cart Handling */
    $supports_html5_storage = ( 'sessionStorage' in window && window['sessionStorage'] !== null );

    $fragment_refresh = {
        url: woocommerce_params.ajax_url,
        type: 'POST',
        data: { action: 'woocommerce_get_refreshed_fragments' },
        success: function( data ) {
            if ( data && data.fragments ) {

                $.each( data.fragments, function( key, value ) {
                    $(key).replaceWith(value);
                });

                if ( $supports_html5_storage ) {
                    sessionStorage.setItem( "wc_fragments", JSON.stringify( data.fragments ) );
                    sessionStorage.setItem( "wc_cart_hash", data.cart_hash );
                }

                $('body').trigger( 'wc_fragments_refreshed' );
            }
        }
    };

    //Always perform fragment refresh
    $.ajax( $fragment_refresh );

    /* Cart hiding */
    if ( $.cookie( "woocommerce_items_in_cart" ) > 0 )
        $('.hide_cart_widget_if_empty').closest('.widget_shopping_cart').show();
    else
        $('.hide_cart_widget_if_empty').closest('.widget_shopping_cart').hide();

    $('body').bind( 'adding_to_cart', function() {
        $('.hide_cart_widget_if_empty').closest('.widget_shopping_cart').show();
    } );
});

Great , works for me

There should be some way from within WPML to invalidate the cart a bit more selectively. But for now, a solution like this seems to work.

If there is anybody here who would be kind enough to explain how to implement this to a beginner, I would greatly appreciate it, thank you :)

@funique

Add code:

/** Break html5 cart caching */
	add_action('wp_enqueue_scripts', 'cartcache_enqueue_scripts', 100);

	function cartcache_enqueue_scripts()
	{
		wp_deregister_script('wc-cart-fragments');
		wp_enqueue_script( 'wc-cart-fragments', get_template_directory_uri()  . '/cart-fragments.js', array( 'jquery', 'jquery-cookie' ), '1.0', true );
	}

to yours "functions.php" in template directory. (/wp-content/themes/your-theme/functions.php)

Then in your template directory (/wp-content/themes/your-theme/) make file "cart-fragments.js" with code:

/** Modified cart-fragments.js script to break HTML5 fragment caching. Useful with WPML when switching languages **/
jQuery(document).ready(function($) {

    /** Cart Handling */
    $supports_html5_storage = ( 'sessionStorage' in window && window['sessionStorage'] !== null );

    $fragment_refresh = {
        url: woocommerce_params.ajax_url,
        type: 'POST',
        data: { action: 'woocommerce_get_refreshed_fragments' },
        success: function( data ) {
            if ( data && data.fragments ) {

                $.each( data.fragments, function( key, value ) {
                    $(key).replaceWith(value);
                });

                if ( $supports_html5_storage ) {
                    sessionStorage.setItem( "wc_fragments", JSON.stringify( data.fragments ) );
                    sessionStorage.setItem( "wc_cart_hash", data.cart_hash );
                }

                $('body').trigger( 'wc_fragments_refreshed' );
            }
        }
    };

    //Always perform fragment refresh
    $.ajax( $fragment_refresh );

    /* Cart hiding */
    if ( $.cookie( "woocommerce_items_in_cart" ) > 0 )
        $('.hide_cart_widget_if_empty').closest('.widget_shopping_cart').show();
    else
        $('.hide_cart_widget_if_empty').closest('.widget_shopping_cart').hide();

    $('body').bind( 'adding_to_cart', function() {
        $('.hide_cart_widget_if_empty').closest('.widget_shopping_cart').show();
    } );
});

BTW. Thanks a lot for that working code!