wp-helpers.php

<?php
/*
*  Return the asset path as variable
* */
function get_asset($url)
{
	return get_template_directory_uri() . '/assets/' . $url;
}

/*
 *  Prints the asset url
 * */
function the_asset($url)
{
	echo asset($url);
}
/**
 * Get image url
 */
function get_image($url){
	return get_asset('images/' . $url);
}

function the_image($url){
	echo get_image($url);
}

/**
 * Help pritty print variable 
 */

function pre($var){
	$styles = [
		'display:block',
		'padding:1em',
		'margin:1em',
		'border-radius:3px',
		'font-size:14px',
		'font-family: monospace',
		'white-space: pre-wrap',
		'word-wrap: break-word',
		'overflow-x:auto',
		'color: #004267',
		'border:1px solid #00426733',
		'box-shadow: 0 1px 1px rgba(0,0,0,0.08)',
		'line-height:1.5em',
		'text-align:left',
		'background-image: linear-gradient(180deg, #eaeaea 50%, #fff 50%)', 
		'background-size: 100% 3em',  // Double the line height 
		'background-position: 0 1em;' // Offset by top padding
	];
	echo sprintf('<pre style="%s">%s</pre>', 
		implode(';', $styles),
		var_export($var, true)
	);
}

/**
 * Get srcset for image
 */
function get_image_srcset($image_id, $image_size){
	if(!empty($image_id)) {
		$image_src = wp_get_attachment_image_url( $image_id, $image_size);
		$image_srcset = wp_get_attachment_image_srcset( $image_id, $image_size );
		return sprintf('src="%1$s" srcset="%2$s"', $image_src, $image_srcset);
	}
}

/**
 *	Helper to get srcset for image to use with lazyload lib
 */
function get_image_lazyload_srcset($image_id, $image_size, $max_width){
	if(!empty($image_id)) {
		// default size
		$image_src = wp_get_attachment_image_url( $image_id, 'medium' );
		$image_srcset = wp_get_attachment_image_srcset( $image_id, $image_size );
		return sprintf('src="%1$s" data-srcset="%2$s" data-sizes=(max-width: %3$s) 100vw, %3$s',
			$image_src,
			$image_srcset,
			$max_width
		);
	}
}

/**
 * Add options ( data-options='{"key":"val"}' )
 */

function get_data_options($options_arr){
	if(!$options_arr || !count($options_arr)){
		return '';
	}
	return sprintf("data-options='%s'", json_encode($options_arr));
}

function the_data_options($options_arr){
	echo get_data_options($options_arr);
}

/**
 * Is doing front-end ajax
 */

function request_is_frontend_ajax()
{
  $script_filename = isset($_SERVER['SCRIPT_FILENAME']) ? $_SERVER['SCRIPT_FILENAME'] : '';
	
  //Try to figure out if frontend AJAX request... If we are DOING_AJAX; let's look closer
  if((defined('DOING_AJAX') && DOING_AJAX)){
  	//From wp-includes/functions.php, wp_get_referer() function.
    //Required to fix: https://core.trac.wordpress.org/ticket/25294
    $ref = '';
    	if ( ! empty( $_REQUEST['_wp_http_referer'] ) ){
				$ref = wp_unslash( $_REQUEST['_wp_http_referer'] );
			} elseif ( ! empty( $_SERVER['HTTP_REFERER'] ) ){
				$ref = wp_unslash( $_SERVER['HTTP_REFERER'] );
			}
			
    //If referer does not contain admin URL and we are using the admin-ajax.php endpoint, this is likely a frontend AJAX request
    if(((strpos($ref, admin_url()) === false) && (basename($script_filename) === 'admin-ajax.php'))){
			return true;
		}
  }
    
	//If no checks triggered, we end up here - not an AJAX request.
  return false;
}