Convert the PHP date format string to a JavaScript date format

function date_format_php_to_js( $php_date_format ) {	
	$formats_php_to_js = array(
		'F j, Y' => 'MM dd, yy',
		'Y/m/d'  => 'yy/mm/dd',
		'm/d/Y'  => 'mm/dd/yy',
		'd/m/Y'  => 'dd/mm/yy',
	);
	return isset( $formats_php_to_js[ $php_date_format ] ) ? $formats_php_to_js[ $php_date_format ] : 'MM dd, yy';
}

Hide all other shipping methods when free shipping is available in WooCommerce

add_filter( 'woocommerce_package_rates', 'hide_shipping_when_free_is_available', 10, 2 );
function hide_shipping_when_free_is_available( $rates, $package ) { 	
 	// Only modify rates if free_shipping is present
  	if ( isset( $rates['free_shipping'] ) ) {  	
  		// To unset a single rate/method, do the following. This example unsets flat_rate shipping
  		unset( $rates['flat_rate'] );  		
  		// To unset all methods except for free_shipping, do the following
  		$free_shipping          = $rates['free_shipping'];
  		$rates                  = array();
  		$rates['free_shipping'] = $free_shipping;
	}	
	return $rates;
}

Hide all WooCommerce breadcrumbs

add_action( 'init', 'hide_woocommerce_breadcrumbs' );
function hide_woocommerce_breadcrumbs() {
    remove_action( 'woocommerce_before_main_content', 'woocommerce_breadcrumb', 20, 0 );
}

Hide the coupon form on the cart or checkout page in WooCommerce

// hide coupon form everywhere
function hide_coupon_field( $enabled ) {
	if ( is_cart() || is_checkout() ) {
		$enabled = false;
	}
	return $enabled;
}
add_filter( 'woocommerce_coupons_enabled', 'hide_coupon_field' );

Change the ‘add to cart’ text in WooCommerce

add_filter( 'woocommerce_product_add_to_cart_text', 'custom_add_to_cart_text' ); // category (archives)
add_filter( 'woocommerce_product_single_add_to_cart_text', 'custom_add_to_cart_text' ); // single
function custom_add_to_cart_text() { 
   return 'My add to cart text';
}