Disable Auto Update Plugin and Theme Emails:

//Disable plugin auto-update email notification
add_filter('auto_plugin_update_send_email', '__return_false');
 
//Disable theme auto-update email notification
add_filter('auto_theme_update_send_email', '__return_false');

Disable Auto Update Core Emails:

//Disable automatic "Your Site Has Been Updated..." emails
add_filter( 'auto_core_update_send_email', 'smartwp_disable_core_update_emails', 10, 4 );
function smartwp_disable_core_update_emails( $send, $type, $core_update, $result ) {
  if ( !empty($type) && $type == 'success' ) {
    return false;
  }
  
  return true;
}

Create File uplad type for custom element:

Create File Upload Type in Visual Composer

How to Create a Circular Progress Button:

An experimental page transition concept for magazines and blogs where an excerpt item opens for a full page view.

Convert hexdec color string to rgb(a) string:

function hex2rgba($color, $opacity = false) {
 
 $default = 'rgb(0,0,0)';
 
 //Return default if no color provided
 if(empty($color))
          return $default; 
 
 //Sanitize $color if "#" is provided 
        if ($color[0] == '#' ) {
         $color = substr( $color, 1 );
        }
 
        //Check if color has 6 or 3 characters and get values
        if (strlen($color) == 6) {
                $hex = array( $color[0] . $color[1], $color[2] . $color[3], $color[4] . $color[5] );
        } elseif ( strlen( $color ) == 3 ) {
                $hex = array( $color[0] . $color[0], $color[1] . $color[1], $color[2] . $color[2] );
        } else {
                return $default;
        }
 
        //Convert hexadec to rgb
        $rgb =  array_map('hexdec', $hex);
 
        //Check if opacity is set(rgba or rgb)
        if($opacity){
         if(abs($opacity) > 1)
         $opacity = 1.0;
         $output = 'rgba('.implode(",",$rgb).','.$opacity.')';
        } else {
         $output = 'rgb('.implode(",",$rgb).')';
        }
 
        //Return rgb(a) color string
        return $output;
}

Here’s a usage example how to use this function for dynamicaly created CSS:

$color = '#ffa226';
$rgb = hex2rgba($color);
$rgba = hex2rgba($color, 0.7);
 
/* CSS output */
 
echo ' 
 div.example{
  background: '.$rgb.';
  color: '.$rgba.';
 }
';

Styling & Customizing File Inputs the Smart Way

.inputfile {
    width: 0.1px;
    height: 0.1px;
    opacity: 0;
    overflow: hidden;
    position: absolute;
    z-index: -1;

    + label {
        font-size: $fontSizeBody;
        line-height: $lineHeightBody;
        color: white;
        display: inline-block;
        cursor: pointer;
    }

    &:focus {
        + label {
            outline: 1px dotted $cBlack;
            outline: -webkit-focus-ring-color auto 5px;
        }
    }
}

/* style 6 */
.inputfile-6 {
    + label {
        color: $cBlue;
        border: 1px solid $cGray;
        padding: 0;

        strong {
            padding: 7px 15px;
            font-weight: 300;
            height: 100%;
            color: $cFont;
            display: inline-block;
            background-color:$cBlueLight;

            @media screen and (max-width: 576px) {
                display: block;
            }
        }

        span {
            padding: 7px 15px;
            font-weight: 300;
            min-width: 150px;
            max-width: 250px;
            min-height: 2em;
            display: inline-block;
            text-overflow: ellipsis;
            white-space: nowrap;
            overflow: hidden;
            vertical-align: top;

            svg path {
                fill: $cBlue;
            }
        }

        &:hover {
            border-color: $cBlack;

            strong {
                background-color:$cBlue;
                color: $cWhite;
            }

            svg path {
                fill: $cWhite;
            }
        }
    }

    &:focus,
    &.has-focus {
        + label {
            border-color: $cBlack;

            strong {
                background-color:$cBlue;
                color: $cWhite;
            }
        }
        svg path {
            fill: $cWhite;
        }
    }
} 

JavaScript:

/*************************************************************
 *************  Custom File Upload Button  ****************
 *************************************************************/

function fileUploadButton() {

    $('.inputfile').each(function () {
        let $input = $(this),
            $label = $input.next('label'),
            labelVal = $label.html();

        $input.on('change', function (e) {
            let fileName = '';

            if (this.files && this.files.length > 1) {
                fileName = (this.getAttribute('data-multiple-caption') || '').replace('{count}', this.files.length);
            } else if (e.target.value) {
                fileName = e.target.value.split('\\').pop();
            }

            if (fileName) {
                $label.find('span').html(fileName);
            } else {
                $label.html(labelVal);
            }
        });

        // Firefox bug fix
        $input
            .on('focus', function () {
                $input.addClass('has-focus');
            })
            .on('blur', function () {
                $input.removeClass('has-focus');
            });
    });

}

JS script

/*************************************************************
 *************  AJAX - Form sending  ****************
 *************************************************************/

function formSubmitTrigger() {

    $('#job-form').on('submit', function (e) {
        e.preventDefault();

        let submit_button = $(this).find('input[type=submit]');

        var data = new FormData(this);

        $.ajax({
            type: "POST",
            dataType: "json",
            url: ajaxurl,
            data: data,
            contentType: false,
            processData: false,
            beforeSend: function () {
                submit_button.attr("disabled", true);
                $(".spinner").show();
            },
            success: function (data) {
                $('.alert-notice').toggle().text(data['data']);
                $('#job-form')[0].reset();
                $(".spinner").hide();
                submit_button.attr("disabled", false);
            },
            error: function (jqXHR, textStatus, errorThrown) {
                $('.alert-notice').toggle().text(data['data']);
                console.log(jqXHR + " :: " + textStatus + " :: " + errorThrown);
            }
        });
    })
}

Ajax function:

function contact_form_ajax(){

    $to = strip_tags($_POST['sendto']);

    $attachments = [];

        //upload file
        if (! function_exists('wp_handle_upload')) {
            require_once(ABSPATH . 'wp-admin/includes/file.php');
        }

        if($_FILES['file']) {
            foreach ($_FILES['file']['name'] as $n => $name) {
                $upload_overrides = ['test_form' => false ];
                $temp_file = $_FILES['file']['tmp_name'][$n];
                $file_name = $_FILES['file']['name'][$n];
                $file_path = WP_CONTENT_DIR . '/uploads/formattachments/' . $file_name;
                
                wp_handle_upload($temp_file, $upload_overrides);
                move_uploaded_file($temp_file, $file_path);
                
                $attachments[] .= $file_path;
            } 
        }


    $subject = "Neue Anfrage!";
    $headers = "From: Hochegger <". $to . ">\r\n";
    $headers .= "Reply-To: ". strip_tags($_POST['Email']) . "\r\n";
    $headers .= "Content-Type: text/html; charset=UTF-8\r\n";

    $message = '<html><body>';
    $message .= '<h2>Neue Anfrage:</h2>';
    foreach ($_POST as $key => $value) {
        if(
            $key != 'action' && 
            $key != 'datenschutz' && 
            $key != 'sendto'
        ) {
         
            $message .= "<strong>" . strip_tags($key) . ": </strong>" . strip_tags($value);
            $message .= "<br/>";
        }
    }
    $message .= "<br/>";
    $message .= "--";
    $message .= "<br/>";
    $message .= "Hochegger Website";
    $message .= "</body></html>";


        //Confirmation email
        $to_confirm = $_POST['Email'];
        $subject_confirm = "Ihre Hochegger Anfrage";
        $headers_confirm = "From: Hochegger <". $to . ">\r\n";
        $headers_confirm .= "MIME-Version: 1.0" . "\r\n";
        $headers_confirm .= "Content-type: text/html; charset=UTF-8" . "\r\n";

        $message_user = '<html><body>';
        $message_user .= '<h2>Ihre Anfrage:</h2>';
        foreach ($_POST as $key => $value) {
            if(
                $key != 'action' && 
                $key != 'datenschutz' && 
                $key != 'sendto'
            ) {
             
                $message_user .= "<strong>" . strip_tags($key) . ": </strong>" . strip_tags($value);
                $message_user .= "<br/>";
            }
        }
        $message_user .= "<br/>";
        $message_user .= "--";
        $message_user .= "<br/>";
        $message_user .= "Hochegger Website";
        $message_user .= "</body></html>";

        wp_mail($to_confirm, $subject_confirm, $message_user, $headers_confirm, $attachments);


    // Here put your Validation and send mail
    $sent = wp_mail($to, $subject, $message, $headers, $attachments);

    if($sent) {
        wp_send_json_success();
        return true;
    }
    else  {
        $message = "Error!";
        $return = array(
            'message' => $message
        );
        wp_send_json_error($return);
    }

    die();
}

add_action('wp_ajax_nopriv_contact_form_ajax', 'contact_form_ajax');
add_action('wp_ajax_contact_form_ajax', 'contact_form_ajax');

This function will connect wp_mail to your authenticated SMTP server

/**
 * This function will connect wp_mail to your authenticated
 * SMTP server. This improves reliability of wp_mail, and 
 * avoids many potential problems.
 *
 * 
 * Values for constants are set in wp-config.php
 */
function send_smtp_email( $phpmailer ) {
    $phpmailer->isSMTP();
    $phpmailer->Host       = SMTP_HOST;
    $phpmailer->SMTPAuth   = SMTP_AUTH;
    $phpmailer->Port       = SMTP_PORT;
    $phpmailer->Username   = SMTP_USER;
    $phpmailer->Password   = SMTP_PASS;
    $phpmailer->SMTPSecure = SMTP_SECURE;
    $phpmailer->From       = SMTP_FROM;
    $phpmailer->FromName   = SMTP_NAME;
}
add_action( 'phpmailer_init', 'send_smtp_email' );

/**
 * SMTP setting for wp_mail -> wp-config.php
 * 
 */
define( 'SMTP_USER',   'email@email.com' );    // Username to use for SMTP authentication
define( 'SMTP_PASS',   'password' );       // Password to use for SMTP authentication
define( 'SMTP_HOST',   'mail.host.com' );    // The hostname of the mail server
define( 'SMTP_FROM',   'email@email.com' ); // SMTP From email address
define( 'SMTP_NAME',   'Reprazent.me' );    // SMTP From name
define( 'SMTP_PORT',   '465' );                  // SMTP port number - likely to be 25, 465 or 587
define( 'SMTP_SECURE', 'ssl' );                 // Encryption system to use - ssl or tls
define( 'SMTP_AUTH',    true );                 // Use SMTP authentication (true|false)
define( 'SMTP_DEBUG',   0 );                    // for debugging purposes only set to 1 or 2

Remove JQuery migrate from WordPress frontend:

function remove_jquery_migrate( $scripts ) {
    if ( ! is_admin() && isset( $scripts->registered['jquery'] ) ) {
        $script = $scripts->registered['jquery'];
        if ( $script->deps ) {
            // Check whether the script has any dependencies
            $script->deps = array_diff( $script->deps, array( 'jquery-migrate' ) );
        }
    }
}
add_action( 'wp_default_scripts', 'remove_jquery_migrate' );

Import Posts from Custom CSV Data:

https://www.sitepoint.com/programmatically-creating-wordpress-posts-from-csv-data/

Example for CPT and ACF fields:

/**
 * Show 'insert posts' button on backend
 */
add_action( "admin_notices", function() {
    echo "<div class='updated'>";
    echo "<p>";
    echo "To insert or overwrite the posts into the CSV files, click the button to the right.";
    echo "<a class='button button-primary' style='margin:0.25em 1em' href='{$_SERVER["REQUEST_URI"]}&insert_km_products'>Import products from CSV</a>";
    echo "</p>";
    echo "</div>";
});

/**
 * Create and insert posts from CSV files
 */
add_action( "admin_init", function() {

    //  the post creation _only_ happens when you want it to.
    if ( ! isset( $_GET["insert_km_products"] ) ) {
        return;
    }

    // Change these to whatever you set
    $custom_names = array(
        "custom-post-type" => "produkte"
    );

    // Get the data from all those CSVs!
    $posts = function() {
        $data = array();
        $errors = array();
        $uploads = wp_upload_dir();
        $upload_path = $uploads['basedir'];

        // Get array of CSV files
        $files = glob( $upload_path."/km_csv/*.csv" );

        foreach ( $files as $file ) {

            // Attempt to change permissions if not readable
            if ( ! is_readable( $file ) ) {
                chmod( $file, 0744 );
            }

            // Check if file is writable, then open it in 'read only' mode
            if ( is_readable( $file ) && $_file = fopen( $file, "r" ) ) {
                $path_parts = pathinfo($file);

                // To sum this part up, all it really does is go row by row, column by column, saving all the data
                $post = array();

                // Get first row in CSV, which is of course the headers
                $header = fgetcsv( $_file, 0, "\t" );

                while ( $row = fgetcsv( $_file, 0, "\t" ) ) {

                    foreach ( $header as $i => $key ) {
                        $post[$key] = $row[$i];
                    }
                    
                    $post['filename'] = $path_parts['filename'];
                    $data[] = $post;
                    
                    // break; // only 1
                }

                fclose( $_file );

            } else {
                $errors[] = "File '$file' could not be opened. Check the file's permissions to make sure it's readable by your server.";
            }
        }

        if ( ! empty( $errors ) ) {
            // ... do stuff with the errors
        }

        return $data;
    };


    //  Check to see if the current post exists within the    
    $post_exists = function( $shop, $id, $import_post_type ) use ( $custom_names ) {
        $product_post = new WP_Query(
            array(
                'post_type'         => $import_post_type,
                'post_status '      => 'publish',
                'meta_query' => array(
                    array(
                        'key'     => 'shop',
                        'value'   => $shop,
                        // 'value'   => 'test',
                    ),
                    array(
                        'key'     => 'id',
                        'value'   => $id,
                    ),
                ),
            )
        );

        return $product_post->post->ID;
    };


    /**
     * IMPORT into post type
     */
    foreach ( $posts() as $post ) {

        $import_post_type = 'produkte';
        $import_taxonomy = 'kategorie';

        switch ($post['filename']) {
            case 'hubmann':
                $product_link = 'http://shop.hubmann-leibnitz.at/';
                break;
            case 'groebner':
                $product_link = 'https://shop.groebner.eu/';
                break;
            case 'blumenversand':
                $product_link = 'https://www.blumenversand.at/';
                break;
            case 'ma-chic':
                $product_link = 'https://shop.ma-chic.at/';
                break;
            default:
                $product_link = $post['Link'];
                break;
        }


        // If the post exists, skip this post and go to the next one
        if ( $existing_post_id = $post_exists( $post["filename"], $post['Id'], $import_post_type ) ) {

            wp_insert_post( array(
                'ID' => $existing_post_id,
                'post_title' => $post['Title'],
                'post_type' => $import_post_type,
                'post_status' => 'publish'
            ));

            $post['post_id'] = $existing_post_id;

        } else {
            // Insert the post into the database
            $post['post_id'] = wp_insert_post( array(
                'post_title' => $post['Title'],
                'post_type' => $import_post_type,
                'post_status' => 'publish'
            ));
        }

        update_field( 'condition', $post['Condition'], $post['post_id'] );
        update_field( 'price', $post['Price'], $post['post_id'] );
        update_field( 'availability', $post['Availability'], $post['post_id'] );
        update_field( 'image_link', $post['Image_Link'], $post['post_id'] );
        update_field( 'category', $post['Category'], $post['post_id'] );
        update_field( 'id', $post['Id'], $post['post_id'] );
        update_field( 'link', $product_link, $post['post_id'] );
        update_field( 'description', $post['Description'], $post['post_id'] );
        update_field( 'gtin', $post['GTIN'], $post['post_id'] );
        update_field( 'brand', $post['Brand'], $post['post_id'] );
        update_field( 'shipping_weight', $post['Shipping_weight'], $post['post_id'] );
        update_field( 'shop', $post['filename'], $post['post_id'] );


        //Assign 'Kategorie' taxonomy
        $args = array(
            'hide_empty' => false,
            'taxonomy'  => $import_taxonomy,
            'meta_query' => array(
                array(
                   'key'       => 'km_id',
                   'value'     => $post['Category'],
                   'compare'   => '='
                )
            ),
            );
        $terms = get_terms( $args );
    
        wp_delete_object_term_relationships( $post['post_id'], $import_taxonomy ); // remove all terms 
        
        if($terms) {
            wp_set_object_terms( $post['post_id'], $terms[0]->term_id, $import_taxonomy ); // assign new terms
        }
    }

});

Page load speed:

function tr_head() {
    $GLOBALS['tr_time_start'] = microtime( true );
}
add_action( 'wp_head', 'tr_head' );

function tr_footer() {
    $start = $GLOBALS['tr_time_start'];
    $end   = microtime( true );
    
    echo sprintf( '<p>Page generated in %0.2f seconds.</p>',
        $end - $start
    );
}
add_action( 'wp_footer', 'tr_footer' );

Add editor the privilege to edit theme & menu:

// get the the role object
$role_object = get_role( 'editor' );

// add $cap capability to this role object

// Design menu point
$role_object->add_cap( 'edit_theme_options' );

//theme settings
$role_object->add_cap( 'manage_options' );

Coupon column – with list of orders coupon was used:

function woo_customer_coupon_column_for_orders( $columns ) {
    $new_columns = array();
    
    foreach ( $columns as $column_key => $column_label ) {
        if ( 'expiry_date' === $column_key ) {
            $new_columns['order_coupons'] = __('Orders', 'woocommerce');
        }
        
        $new_columns[$column_key] = $column_label;
    }
    return $new_columns;
}
add_filter( 'manage_edit-shop_coupon_columns', 'woo_customer_coupon_column_for_orders' );


function woo_display_customer_coupon_in_column_for_orders( $column ) {
    global $the_order, $post;
    if( $column  == 'order_coupons' ) {

        $orders_with_coupon = wh_getOrderbyCouponCode($post->post_title);
        foreach ($orders_with_coupon as $order) {

            echo '- <a href="'.get_admin_url().'/post.php?post='.$order.'&action=edit"><small><em>#' . $order . '</em></small></a>';
            echo '<br/>';
        }
    }
}
add_action( 'manage_shop_coupon_posts_custom_column' , 'woo_display_customer_coupon_in_column_for_orders' );



function wh_getOrderbyCouponCode($coupon_code) {
    global $wpdb;
    $return_array = [];

    $query = "SELECT
        p.ID AS order_id
        FROM
        {$wpdb->prefix}posts AS p
        INNER JOIN {$wpdb->prefix}woocommerce_order_items AS woi ON p.ID = woi.order_id
        WHERE
        p.post_type = 'shop_order' AND
        p.post_status IN ('" . implode("','", array_keys(wc_get_order_statuses())) . "') AND
        woi.order_item_type = 'coupon' AND
        woi.order_item_name = '" . $coupon_code . "';";

    $orders = $wpdb->get_results($query);

    if (!empty($orders)) {
        $dp = ( isset($filter['dp']) ? intval($filter['dp']) : 2 );
        //looping throught all the order_id
        foreach ($orders as $key => $order) {
            $order_id = $order->order_id;
            $return_array[$key] = $order_id;
        }

    }
    return $return_array;
}

Disable WordPress Updates for Specific Users (Not admin user):

function disable_updates() {
    global $wp_version;
    return (object) array( 'last_checked' => time(), 'version_checked' => $wp_version, );
}

add_action( 'init', function () {
    if ( ! current_user_can( 'administrator' ) ) {
        add_filter( 'pre_site_transient_update_core', 'disable_updates' );     // Disable WordPress core updates
        add_filter( 'pre_site_transient_update_plugins', 'disable_updates' );  // Disable WordPress plugin updates
        add_filter( 'pre_site_transient_update_themes', 'disable_updates' );   // Disable WordPress theme updates
    }
} );

A snippet for generating a URL friendly slug in PHP

function slugify($string){
return strtolower(trim(preg_replace('/[^A-Za-z0-9-]+/', '-', $string), '-'));
}

Reset user roles. Run once.

if ( !function_exists( 'populate_roles' ) ) {
require_once( ABSPATH . 'wp-admin/includes/schema.php' );
}

populate_roles();

https://www.isitwp.com/track-post-views-without-a-plugin-using-post-meta/

Are you looking for a way to track post views without a plugin using post meta? While there’s probably a plugin for this, we have created a quick code snippet that you can use to track post views without a plugin using post meta in WordPress.

Instructions:

Add this code to your theme’s functions.php file:

function getPostViews($postID){
    $count_key = 'post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
        return "0 View";
    }
    return $count.' Views';
}
function setPostViews($postID) {
    $count_key = 'post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        $count = 0;
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
    }else{
        $count++;
        update_post_meta($postID, $count_key, $count);
    }
}
 
// Remove issues with prefetching adding extra views
remove_action( 'wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0); 

Optionally add this code as well to a column in the WordPress admin that displays the post views:

// Add to a column in WP-Admin
add_filter('manage_posts_columns', 'posts_column_views');
add_action('manage_posts_custom_column', 'posts_custom_column_views',5,2);
function posts_column_views($defaults){
    $defaults['post_views'] = __('Views');
    return $defaults;
}
function posts_custom_column_views($column_name, $id){
    if($column_name === 'post_views'){
        echo getPostViews(get_the_ID());
    }
}

This part of the tracking views code will set the post views. Just place this code below within the single.php file inside the WordPress Loop.

<?php setPostViews(get_the_ID()); ?>

Note about fragment caching: If you are using a caching plugin like W3 Total Cache, the method above to set views will not work as the setPostViews() function would never run. However, W3 Total Cache has a feature called fragment caching. Instead of the above, use the following so the setPostViews() will run just fine and will track all your post views even when you have caching enabled.

<!-- mfunc setPostViews(get_the_ID()); --><!-- /mfunc -->

The code below is optional. Use this code if you would like to display the number of views within your posts. Place this code within the Loop.

<?php echo getPostViews(get_the_ID());?>

Hide WP version:

function remove_version() {
    return '';
}
add_filter('the_generator', 'remove_version');

get_header() Fatal error PHP (boti dostopajo do index.php).
Dodamo v index.php namesto get_header():

if (function_exists('get_header')) {
    get_header();
} else {
    die();
}

echo substr(get_the_excerpt(), 0,200)."…";

Additional options:
– http://smallenvelop.com/limit-post-excerpt-length-in-wordpress/

Renaming standard post category:

function revcon_change_cat_object() {
    global $wp_taxonomies;
    $labels = &$wp_taxonomies['category']->labels;
    $labels->name = 'Kategorie';
    $labels->singular_name = 'Kategorie';
    $labels->add_new = 'Add Kategorie';
    $labels->add_new_item = 'Add Kategorie';
    $labels->edit_item = 'Edit Kategorie';
    $labels->new_item = 'Kategorie';
    $labels->view_item = 'View Kategorie';
    $labels->search_items = 'Search Kategorien';
    $labels->not_found = 'No Kategorie found';
    $labels->not_found_in_trash = 'No Kategorie found in Trash';
    $labels->all_items = 'Alle Kategorien';
    $labels->menu_name = 'Kategorie';
    $labels->name_admin_bar = 'Kategorie';
}
add_action( 'init', 'revcon_change_cat_object' );

Renamin standart post post_type:

function revcon_change_post_label() {
    global $menu;
    global $submenu;
    $menu[5][0] = 'Novice';
    $submenu['edit.php'][5][0] = 'Novice';
    $submenu['edit.php'][10][0] = 'Dodaj novico';
}
function revcon_change_post_object() {
    global $wp_post_types;
    $labels = &$wp_post_types['post']->labels;
    $labels->name = 'Novice';
    $labels->singular_name = 'Novice';
    $labels->add_new = 'Dodaj Novico';
    $labels->add_new_item = 'Dodaj Novico';
    $labels->edit_item = 'Uredi novico';
    $labels->new_item = 'Novica';
    $labels->view_item = 'Poglej novico';
    $labels->search_items = 'Išči novice';
    $labels->not_found = 'Ni najdenih novic';
    $labels->not_found_in_trash = 'Ni novic v smeteh';
    $labels->all_items = 'Vse novice';
    $labels->menu_name = 'Novice';
    $labels->name_admin_bar = 'Novice';
}
 
add_action( 'admin_menu', 'revcon_change_post_label' );
add_action( 'init', 'revcon_change_post_object' );

//EN NEWS
function revcon_change_post_label() {
    global $menu;
    global $submenu;
    $menu[5][0] = 'News';
    $submenu['edit.php'][5][0] = 'News';
    $submenu['edit.php'][10][0] = 'Add News';
}
function revcon_change_post_object() {
    global $wp_post_types;
    $labels = &$wp_post_types['post']->labels;
    $labels->name = 'News';
    $labels->singular_name = 'News';
    $labels->add_new = 'Add News';
    $labels->add_new_item = 'Add News';
    $labels->edit_item = 'Edit News';
    $labels->new_item = 'News';
    $labels->view_item = 'View News';
    $labels->search_items = 'Search News';
    $labels->not_found = 'No found News';
    $labels->not_found_in_trash = 'No News in trash';
    $labels->all_items = 'All News';
    $labels->menu_name = 'News';
    $labels->name_admin_bar = 'News';
}
 
add_action( 'admin_menu', 'revcon_change_post_label' );
add_action( 'init', 'revcon_change_post_object' );

Initial enqueue theme scripts/styles:

function enqueue_scripts() {   

    wp_enqueue_style( 'flexslider-css', get_stylesheet_directory_uri().'/js/flexslider/flexslider.css' );
    wp_enqueue_script('parodontologija_script', get_stylesheet_directory_uri() . '/js/scripts.js', '1.0.0', true);

}
add_action('wp_enqueue_scripts', 'enqueue_scripts');

Register image thumbnails:

function images_setup() {    
    add_image_size( 'gallery-thumb', 805, 434, true);
}    
add_action('after_setup_theme', 'images_setup');

Backend editor dropdown thumbnail select:

function my_custom_sizes( $sizes ) {
    return array_merge( $sizes, array(
        'gallery-thumb' => __('Gallery Main'),
        ) );
    }
add_filter( 'image_size_names_choose', 'my_custom_sizes' );