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How to modify a payment form in a wordpress plugin?

I'm trying to create a food delivery web page with the wordpress restropress plugin,
the page looks like this: https://restropress.magnigenie.com/demo/food-items/
And the problem I have is that in the checkout form I want to remove the city field
since being a delivery I obviously only make deliveries in my city
and I don't want my customers to go through that redundancy.
I would also like to change the postcode field from text to a drop-down.
I have tried with some action hooks setting as "unset" the field "city" but nothing.
In the html of the page I managed to make the changes directly
but when I updated the plug-in changes were lost.
Can you help me? This is the plugins code that I'm trying to modify:
<fieldset id="rpress_checkout_order_details">
<legend><?php echo apply_filters( 'rpress_checkout_order_details_text', esc_html__( 'Order Details', 'restropress' ) ); ?></legend>
<?php do_action( 'rpress_purchase_form_before_order_details' ); ?>
<?php
if( rpress_selected_service() == 'delivery' ) :
$customer = RPRESS()->session->get( 'customer' );
$customer = wp_parse_args( $customer, array( 'delivery_address' => array(
'address' => '',
'flat' => '',
'city' => '',
'postcode' => '',
) ) );
$customer['delivery_address'] = array_map( 'sanitize_text_field', $customer['delivery_address'] );
if( is_user_logged_in() ) {
$user_address = get_user_meta( get_current_user_id(), '_rpress_user_delivery_address', true );
foreach( $customer['delivery_address'] as $key => $field ) {
if ( empty( $field ) && ! empty( $user_address[ $key ] ) ) {
$customer['delivery_address'][ $key ] = $user_address[ $key ];
} else {
$customer['delivery_address'][ $key ] = '';
}
}
}
$customer['delivery_address'] = apply_filters( 'rpress_delivery_address', $customer['delivery_address'] );
?>
<p id="rpress-street-address" class="rp-col-md-6 rp-col-sm-12">
<label class="rpress-street-address" for="rpress-street-address">
<?php esc_html_e('Street Address', 'restropress') ?>
<span class="rpress-required-indicator">*</span>
</label>
<input class="rpress-input" type="text" name="rpress_street_address" id="rpress-street-address" placeholder="<?php esc_html_e('Street Address', 'restropress'); ?>" value="<?php echo $customer['delivery_address']['address']; ?>" />
</p>
<p id="rpress-apt-suite" class="rp-col-md-6 rp-col-sm-12">
<label class="rpress-apt-suite" for="rpress-apt-suite">
<?php esc_html_e('Apartment, suite, unit etc. (optional)', 'restropress'); ?>
</label>
<input class="rpress-input" type="text" name="rpress_apt_suite" id="rpress-apt-suite" placeholder="<?php esc_html_e('Apartment, suite, unit etc. (optional)', 'restropress'); ?>" value="<?php echo $customer['delivery_address']['flat']; ?>" />
</p>
<p id="rpress-city" class="rp-col-md-6 rp-col-sm-12">
<label class="rpress-city" for="rpress-city">
<?php _e('Town / City', 'restropress') ?>
<span class="rpress-required-indicator">*</span>
</label>
<input class="rpress-input" type="text" name="rpress_city" id="rpress-city" placeholder="<?php _e('Town / City', 'restropress') ?>" value="<?php echo $customer['delivery_address']['city']; ?>" />
</p>
<p id="rpress-postcode" class="rp-col-md-6 rp-col-sm-12">
<label class="rpress-postcode" for="rpress-postcode">
<?php _e('Postcode / ZIP', 'restropress') ?>
<span class="rpress-required-indicator">*</span>
</label>
<input class="rpress-input" type="text" name="rpress_postcode" id="rpress-postcode" placeholder="<?php _e('Postcode / ZIP', 'restropress') ?>" value="<?php echo $customer['delivery_address']['postcode']; ?>" />
</p>
<?php endif; ?>
<p id="rpress-order-note" class="rp-col-sm-12">
<label class="rpress-order-note" for="rpress-order-note"><?php echo sprintf( __('%s Instructions', 'restropress'), rpress_selected_service( 'label' ) ); ?></label>
<textarea name="rpress_order_note" class="rpress-input" rows="5" cols="8" placeholder="<?php echo sprintf( __('Add %s instructions (optional)', 'restropress'), strtolower( rpress_selected_service( 'label' ) ) ); ?>"></textarea>
</p>
<?php do_action( 'rpress_purchase_form_order_details' ); ?>
<?php do_action( 'rpress_purchase_form_order_details_fields' ); ?>
</fieldset>
I put this following hook in the functions.php file and it didn't work:
function wp_edit_checkout_fields($fields){
unset($fields['delivery_adress']['city']);
return $fields;
}
add_filter('rpress_purchase_form_order_details_fields', 'wp_edit_checkout_fields');

Note that, there is do_action( 'rpress_purchase_form_order_details_fields' ); in the plugin code. It is usually used with add_action, but not with add_filter.
Maybe you could take advantage of this filter call:
$customer['delivery_address'] = apply_filters( 'rpress_delivery_address', $customer['delivery_address'] );
Try something like this (put in your function.php file):
function your_custom_function($delivery_address) {
// Try to somehow process the city field here...
// First, you could output a variable
// to understand the data structure
print_r($delivery_address);
// and return the changed address
return $delivery_address;
}
add_filter( 'rpress_delivery_address', 'your_custom_function' );
Docs - https://developer.wordpress.org/reference/functions/add_filter/

Custom plus and minus quantity buttons in Woocommerce 3

I’m building custom WordPress and WooCommerce theme and adding custom plus and minus buttons to Product page quantity field. The buttons do update quantity input's value and I also receive "Item has been added to your cart" notification (on Product page) when I submit Add to Cart. But the cart page doesn’t show any items, neither says the cart is empty.
I can not work out which WooCommerce JS function I’m suppose to hook into, neither how to hook into it. Could I ask for help please?!
Thanks in advance!
My HTML layout:
<div class="quantity">
<label class="quantity__label" for="<?php echo esc_attr( $input_id ); ?>"><?php esc_html_e( 'Quantity:', 'woocommerce' ); ?></label>
<div class="quantity__wrapper">
<input type="button" value="-" class="quantity__button quantity__remove js-qty-remove" />
<input
type="text"
id="<?php echo esc_attr( $input_id ); ?>"
class="input-text qty text quantity__input"
step="<?php echo esc_attr( $step ); ?>"
min="<?php echo esc_attr( $min_value ); ?>"
max="<?php echo esc_attr( 0 < $max_value ? $max_value : '' ); ?>"
name="<?php echo esc_attr( $input_name ); ?>"
value="<?php echo esc_attr( $input_value ); ?>"
title="<?php echo esc_attr_x( 'Qty', 'Product quantity input tooltip', 'woocommerce' ); ?>"
size="4"
pattern="<?php echo esc_attr( $pattern ); ?>"
inputmode="<?php echo esc_attr( $inputmode ); ?>"
aria-labelledby="<?php echo esc_attr( $labelledby ); ?>" />
<input type="button" value="+" class="quantity__button quantity__add js-qty-add" />
</div>
</div>
My custom jQuery function:
function quantityButtons() {
var $qtyAdd = $('.js-qty-add'),
$qtyRemove = $('.js-qty-remove'),
$qtyInput = $('.quantity__input');
$qtyAdd.on('click', addQty);
$qtyRemove.on('click', removeQty);
function addQty() {
var $qtyInput = $('.quantity__input'),
$qtyRemove = $('.js-qty-remove'),
$i = $qtyInput.val();
$i++;
$qtyRemove.attr("disabled", !$i);
$qtyInput.val($i);
}
function removeQty() {
var $qtyInput = $('.quantity__input'),
$qtyRemove = $('.js-qty-remove'),
$i = $qtyInput.val();
if ($i >= 1) {
$i--;
$qtyInput.val($i);
} else {
$qtyRemove.attr("disabled", true);
}
}
$qtyRemove.attr("disabled", !$qtyInput.val());
}
quantityButtons();

Your First code part is made from a customization of global/quantity-input.php Woocommerce template code…
So for testing, I have changed partially that global/quantity-input.php template code with the following (very near to your code):
?>
<div class="quantity">
<label class="screen-reader-text" for="<?php echo esc_attr( $input_id ); ?>"><?php esc_html_e( 'Quantity', 'woocommerce' ); ?></label>
<input type="button" value="-" class="qty_button minus" />
<input
type="number"
id="<?php echo esc_attr( $input_id ); ?>"
class="input-text qty text"
step="<?php echo esc_attr( $step ); ?>"
min="<?php echo esc_attr( $min_value ); ?>"
max="<?php echo esc_attr( 0 < $max_value ? $max_value : '' ); ?>"
name="<?php echo esc_attr( $input_name ); ?>"
value="<?php echo esc_attr( $input_value ); ?>"
title="<?php echo esc_attr_x( 'Qty', 'Product quantity input tooltip', 'woocommerce' ); ?>"
size="4"
pattern="<?php echo esc_attr( $pattern ); ?>"
inputmode="<?php echo esc_attr( $inputmode ); ?>"
aria-labelledby="<?php echo esc_attr( $labelledby ); ?>" />
<input type="button" value="+" class="qty_button plus" />
</div>
<?php
Now the necessary CSS and revisited jQuery code functions:
// Minimum CSS to remove +/- default buttons on input field type number
add_action( 'wp_head' , 'custom_quantity_fields_css' );
function custom_quantity_fields_css(){
?>
<style>
.quantity input::-webkit-outer-spin-button,
.quantity input::-webkit-inner-spin-button {
display: none;
margin: 0;
}
.quantity input.qty {
appearance: textfield;
-webkit-appearance: none;
-moz-appearance: textfield;
}
</style>
<?php
}
add_action( 'wp_footer' , 'custom_quantity_fields_script' );
function custom_quantity_fields_script(){
?>
<script type='text/javascript'>
jQuery( function( $ ) {
if ( ! String.prototype.getDecimals ) {
String.prototype.getDecimals = function() {
var num = this,
match = ('' + num).match(/(?:\.(\d+))?(?:[eE]([+-]?\d+))?$/);
if ( ! match ) {
return 0;
}
return Math.max( 0, ( match[1] ? match[1].length : 0 ) - ( match[2] ? +match[2] : 0 ) );
}
}
// Quantity "plus" and "minus" buttons
$( document.body ).on( 'click', '.plus, .minus', function() {
var $qty = $( this ).closest( '.quantity' ).find( '.qty'),
currentVal = parseFloat( $qty.val() ),
max = parseFloat( $qty.attr( 'max' ) ),
min = parseFloat( $qty.attr( 'min' ) ),
step = $qty.attr( 'step' );
// Format values
if ( ! currentVal || currentVal === '' || currentVal === 'NaN' ) currentVal = 0;
if ( max === '' || max === 'NaN' ) max = '';
if ( min === '' || min === 'NaN' ) min = 0;
if ( step === 'any' || step === '' || step === undefined || parseFloat( step ) === 'NaN' ) step = 1;
// Change the value
if ( $( this ).is( '.plus' ) ) {
if ( max && ( currentVal >= max ) ) {
$qty.val( max );
} else {
$qty.val( ( currentVal + parseFloat( step )).toFixed( step.getDecimals() ) );
}
} else {
if ( min && ( currentVal <= min ) ) {
$qty.val( min );
} else if ( currentVal > 0 ) {
$qty.val( ( currentVal - parseFloat( step )).toFixed( step.getDecimals() ) );
}
}
// Trigger change event
$qty.trigger( 'change' );
});
});
</script>
<?php
}
Code goes in function.php file of your active child theme (or active theme). Tested and works.
The quantity buttons "plus" and "minus" work perfectly and are displayed this way:
Products are added to cart with the correct quantity:
if you change the quantity field value with plus and minus buttons, the "Update cart" button is activated when any quantity field change.
When you click on "Update cart", the quantities as correctly updated.

/* Show Buttons */
add_action( 'woocommerce_before_add_to_cart_quantity', 'display_quantity_plus' );
function display_quantity_plus() {
echo '<button type="button" class="plus" >+</button>';
}
add_action( 'woocommerce_after_add_to_cart_quantity', 'display_quantity_minus' );
function display_quantity_minus() {
echo '<button type="button" class="minus" >-</button>';
}
//Note: to place minus # left and plus # right replace above add_actions with:
//add_action( 'woocommerce_before_add_to_cart_quantity', 'display_quantity_minus' );
//add_action( 'woocommerce_after_add_to_cart_quantity', 'display_quantity_plus' );
add_action( 'wp_footer', 'add_cart_quantity_plus_minus' );
function add_cart_quantity_plus_minus() {
// Only run this on the single product page
if ( ! is_product() ) return;
?>
<script type="text/javascript">
jQuery(document).ready(function($){
$('form.cart').on( 'click', 'button.plus, button.minus', function() {
// Get current quantity values
var qty = $( this ).closest( 'form.cart' ).find( '.qty' );
var val = parseFloat(qty.val());
var max = parseFloat(qty.attr( 'max' ));
var min = parseFloat(qty.attr( 'min' ));
var step = parseFloat(qty.attr( 'step' ));
// Change the value if plus or minus
if ( $( this ).is( '.plus' ) ) {
if ( max && ( max <= val ) ) {
qty.val( max );
} else {
qty.val( val + step );
}
} else {
if ( min && ( min >= val ) ) {
qty.val( min );
} else if ( val > 1 ) {
qty.val( val - step );
}
}
});
});
</script>
//add css
.single-product div.product form.cart .quantity {
float: none;
margin: 0;
display: inline-block;
}

Dynamically add and remove post title

In my wordpress website i create an Ajax search and search post_title. The code is here...
Function and script:
<?php
add_action( 'wp_footer', 'ajax_fetch' );
function ajax_fetch() {
?>
<script type="text/javascript">
function fetch(){
jQuery.ajax({
url: ajaxwpse.ajaxurl,
type: 'post',
data: { action: 'data_fetch', keyword: jQuery('#keyword').val() },
success: function(data) {
jQuery('#datafetch').html( data );
}
});
}
</script>
<?php
}
add_action('wp_ajax_data_fetch' , 'data_fetch');
add_action('wp_ajax_nopriv_data_fetch','data_fetch');
function data_fetch(){
if ( esc_attr( $_POST['keyword'] ) == null ) { die(); }
$the_query = new WP_Query( array( 'posts_per_page' => -1, 's' => esc_attr( $_POST['keyword'] ), 'post_type' => array('mobile','tablet') ) );
if( $the_query->have_posts() ) :
while( $the_query->have_posts() ): $the_query->the_post(); ?>
<div>
<button class="post-link" rel="<?php the_ID(); ?>"> ADD </button>
<li><?php the_title();?></li>
</div>
<?php endwhile;
wp_reset_postdata();
endif;
die();
}
After sucessfully search with Ajax Now i need to add post_title from search to div id="post-container" dynamically.
HTML
<input type="text" name="keyword" id="keyword" onkeyup="fetch()" placeholder="Search to add"></input>
<div id="datafetch"></div> // successfuly ajax Search Result Here
<div id="post-container"> </div> // Trying to add post title here
I create a ADD button in search result to add post_title into div.
How dynamically add post_title from search field to div with button?

You've to attach click event to your button the get the post_title and append it to the div :
$(function(){
$('body').on('click', '.post-link', function(){
var post_title = $(this).closest('div').find('a').text();
$('#post-container').append( post_title );
});
});
Hope this helps.
$(function(){
$('body').on('click', '.post-link', function(){
var post_title = $(this).closest('div').find('a').text();
if( $('#post-container p').length < 4 )
$('#post-container').append( '<p>' + post_title + ' ------ REMOVE</p>' );
else
alert('You could add max 4 titles');
});
$('body').on('click', '.remove-title', function(){
$(this).closest('p').remove();
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div>
<button class="post-link"> ADD </button>
<li>
The title 1 HERE
</li>
</div>
<div>
<button class="post-link"> ADD </button>
<li>
The title 2 HERE
</li>
</div>
<div>
<button class="post-link"> ADD </button>
<li>
The title 3 HERE
</li>
</div>
<hr>
<div id="post-container"> </div>

Compose both divs in your PHP function, then put them in a single <div>, like this:
PHP:
add_action('wp_ajax_nopriv_data_fetch','data_fetch');
function data_fetch(){
if ( esc_attr( $_POST['keyword'] ) == null ) { die(); }
$the_query = new WP_Query( array( 'posts_per_page' => -1, 's' => esc_attr( $_POST['keyword'] ), 'post_type' => array('mobile','tablet') ) );
if( $the_query->have_posts() ) :
// compose $post_title
$post_title = "...";
echo "<div id=\"datafetch\">";
while( $the_query->have_posts() ): $the_query->the_post(); ?>
<div>
<button class="post-link" rel="<?php the_ID(); ?>"> ADD </button>
<li><?php the_title();?></li>
</div>
<?php endwhile;
echo "</div><div id=\"post-container\">" . $post_title . "</div>";
wp_reset_postdata();
endif;
die();
}
HTML:
<input type="text" name="keyword" id="keyword" onkeyup="fetch()" placeholder="Search to add"></input>
<div id="result"></div>
JS:
// in your ajax call
success: function(data) {
jQuery('#result').html( data );
}

jQuery Unknown Issue with field styles

I'm learning JS/jQuery mainly for implementing AJAX in my WordPress projects.
After hours of headache trying to figure out what's wrong with this code I decided to post it here, hoping somebody nice will help me.
My contact form JS script is not working as expected.
I can't figure out why after click on the submit button, the css rules of the required fields don't change on the page.
The jQuery script:
jQuery( document ).ready( function( $ ) {
if ( $( '#mystcf-send' ).length > 0 ) {
alert( 'Everything OK' ); // We enter in the condition... as expected.
$( 'body' ).append( '<div id="noty"></div>' );
$( '#mystcf-send' ).click( function() {
var busy = false,
error = false,
form = $( this ).parent( 'form' );
alert( 'Everything OK' ); // After click on '#mystcf-send' button, the alert box popin, the code is excecuting normally untill here...
form.find( '[required]' ).each( function() {
alert(); // After click on #mystcf button, this alert box is NOT displaying... and so the conditions below are not working.
if( $.trim( $( this ).val() ) == '' ) {
$( this ).css( 'border-color', '#FF0000' );
error = true;
}
else {
$( this ).css( 'border-color', '#CDCDCD' );
}
} );
return false;
} );
}
} );
The PHP script:
<?php
if ( ! defined( 'ABSPATH' ) ) exit;
add_shortcode( 'mystcf', 'mystcf_shortcode' );
add_action( 'wp_enqueue_scripts', 'mystcf_scripts' );
function mystcf_scripts() {
if ( is_page( 'contact' ) ) :
wp_register_script( 'mystcf-script', get_stylesheet_directory_uri() . '/inc/contact-form/js/jquery-contact-form.js', array( 'jquery' ) );
wp_localize_script( 'mystcf-script', 'mystcf_ajax', array( 'url' => admin_url( 'admin-ajax.php' ) ) );
wp_enqueue_script( 'mystcf-script' );
endif;
}
function mystcf_shortcode() {
ob_start();
mystcf_template();
$contact_form = ob_get_clean();
return $contact_form;
}
function mystcf_template() { ?>
<div class="mystcf-container">
<form id="mystcf">
<div class="mystcf-left-panel">
<p>
<label for="mystcf-email">Email <abbr class="required" title="<?php esc_attr( __( 'Required', 'mystorefront' ) ); ?>">*</abbr></label><br />
<input type="email" id="mystcf-email" name="mystcf_email" value="<?php if ( isset( $_POST['mystcf_email'] ) ) echo esc_attr( $_POST['mystcf_email'] ); ?>" required />
</p>
<p>
<label for="mystcf-first-name">Prénom</label><br />
<input type="text" id="mystcf-first-name" name="mystcf_first_name" value="<?php if ( isset( $_POST['mystcf_first_name'] ) ) echo esc_attr( $_POST['mystcf_first_name'] ); ?>" />
</p>
<p>
<label for="mystcf-second-name">Nom</label><br />
<input type="text" id="mystcf-second-name" name="mystcf_second_name" value="<?php if ( isset( $_POST['mystcf_second_name'] ) ) echo esc_attr( $_POST['mystcf_second_name'] ); ?>" />
</p>
<p>
<label for="mystcf-tel">Téléphone</label><br />
<input type="tel" id="mystcf-tel" name="mystcf_tel" value="<?php if ( isset( $_POST['mystcf_tel'] ) ) echo esc_attr( $_POST['mystcf_tel'] ); ?>" />
</p>
</div>
<div class="mystcf-right-panel">
<p>
<label for="mystcf-message">Message <abbr class="required" title="<?php esc_attr( __( 'Required', 'mystorefront' ) ); ?>">*</abbr></label><br />
<textarea type="text" id="mystcf-message" name="mystcf_message" rows="17" required><?php if ( isset( $_POST['mystcf_message'] ) ) echo esc_textarea( $_POST['mystcf_message'] ); ?></textarea>
</p>
</div>
<?php wp_nonce_field( '', 'security' ); ?>
<input type="hidden" name="mystcf_sent" value="1">
<p>
<input type="submit" class="mystcf-send" id="mystcf-send" value="<?php esc_attr( __( 'Send', 'mystorefront' ) ); ?>">
</p>
</form>
</div><?php
}

The problem is with the line where you search the form. It should be this:
form = $(this).closest('form');
parent() returns the parent (and only if it matches the selector specified). On the other hand, closest() searches all ancestors and return the first match.

How to invite friends on wordpress without being logged in to the system [closed]

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Want to improve this question? Update the question so it focuses on one problem only by editing this post.
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So I downloaded this great addon for wordpress called Invite Friends to Register - Link
And I wanted to tweak the code so that anyone who sees this page can invite their friends.
Can anyone help please? Much appreciated!
Here is the code
Thanks!
/**
* returns the javascript and form code for an ajax invite form
*/
function invfr_form() {
global $post, $invfr_add_scripts;
$invfr_add_scripts = true;
// only allow the form to be used if the user is logged in.
// Offer a login link that redirects back to the page the form
// was trying to be called on
if ( !is_user_logged_in() )
$output = sprintf( __( 'You must be logged in to invite friends. Log in', 'invfr'), wp_login_url( get_permalink( $post->ID ) ) );
else {
$user = wp_get_current_user();
$user_id = $user->ID;
$user_name = $user->user_firstname ? $user->user_firstname : $user->user_nicename;
$user_email = $user->user_email;
ob_start(); ?>
<script type="text/javascript">
var jQuery = jQuery.noConflict();
jQuery(window).load(function(){
jQuery('#invfr_form').submit(function() {
// change visual indicators
jQuery('td').removeClass('error');
jQuery('.loading').show();
jQuery('.submit input').attr('disabled', 'disabled');
// validate and process form here
var str = jQuery(this).serialize();
jQuery.ajax({
type: 'POST',
url: '<?php echo admin_url( 'admin-ajax.php' ); ?>',
data: str,
success: function(msg) {
jQuery('#invfr_note').ajaxComplete(function(event, request, settings) {
msg = msg.replace(/(\s+)?.$/, "");
if( msg == 'sent' ) {
result = '<div class="updated"><p><?php _e( 'Your invitation has been sent! Send another?', 'invfr' ); ?></p></div>';
jQuery('#invfr_form input[type=text], #invfr_form input[type=email]').val('');
} else {
//loop through the error items to indicate which fields have errors
msg = msg.replace(/[\[\]']+/g,'');
msg = msg.split(',');
jQuery.each( msg, function ( i, id ) {
id = id.replace(/["']{1}/g, '');
jQuery(id).parent('td').addClass('error');
});
result = '<div class="error"><p><?php _e( '<strong>ERROR:</strong> Check your form for the errors which are highlighted below.', 'invfr' ); ?></p></div>';
//result = msg;
msg = '';
}
jQuery(this).html(result);
// visual indicators
jQuery('.loading').hide();
jQuery('.submit input').removeAttr('disabled');
});
}
});
return false;
});
});
</script>
<div id="invfr_form_container">
<p><?php echo sprintf( __( 'Enter your friend’s name and email address to send them an invitation to register at %s', 'invfr' ), get_option( 'blogname' ) ); ?>
<div id="invfr_note"></div>
<form id="invfr_form" action="">
<table class="form-table">
<thead>
<tr>
<th><?php _e( 'Friend’s Name', 'invfr' ); ?></th>
<th><?php _e( 'Friend’s Email', 'invfr' ); ?></th>
<th><a class="invfr_add button" href="#">+</a></th>
</tr>
</thead>
<tr>
<td valign="top"><label for="friend_name-0" class="screen-reader-text"><?php _e( 'Friend’s Name', 'invfr' ); ?></label>
<input type="text" name="friend_name[0]" id="friend_name-0" value="" />
<span class="error-msg"><?php _e( 'Enter your friend’s name', 'invfr' ); ?></span>
</td>
<td valign="top"><label for="friend_email-0" class="screen-reader-text"><?php _e( 'Friend’s Email', 'invfr' ); ?></label>
<input type="email" name="friend_email[0]" id="friend_email-0" value="" />
<span class="error-msg"><?php _e( 'Enter a valid email address', 'invfr' ); ?></span>
</td>
<td><a class="invfr_remove button" href="#">-</a></td>
</tr>
</table>
<p class="submit"><input type="submit" value="<?php _e( 'Send Invitation', 'invfr' ); ?>" class="button button-primary" />
<img src="<?php echo get_option( 'siteurl'); ?>/wp-admin/images/loading.gif" class="loading" /></p>
<input type="hidden" name="user_id" value="<?php echo $user_id; ?>" />
<input type="hidden" name="user_name" value="<?php echo $user_name; ?>" />
<input type="hidden" name="user_email" value="<?php echo $user_email; ?>" />
<input type="hidden" name="action" value="invfr_process_ajax"/>
</form>
</div>
<?php
$output = ob_get_contents();
ob_clean();
}
return $output;
}
// Template tag
if ( !function_exists( 'invite_friends' ) ) {
function invite_friends( ) {
echo invfr_form();
}
}
// Shortcode
add_shortcode( 'invite_friends', 'invfr_form' );
/**
* callback for the users page that allows you to invite friends from the admin
*/
function invfr_invite_friends_page() {
?>
<div class="wrap">
<?php screen_icon(); ?>
<h2><?php _e( 'Invite Friends', 'invfr' ); ?></h2>
<?php settings_errors(); ?>
<?php echo invfr_form(); ?>
</div>
<?php
}

It looks like it might be as easy as just removing the conditional statement that checks if the user is logged in:
if ( !is_user_logged_in() )
$output = sprintf( __( 'You must be logged in to invite friends. Log in', 'invfr'), wp_login_url( get_permalink( $post->ID ) ) );
else {
and the closing } wherever it is