Google-Sitelinks-JSON-LD for AdSense

Google-Sitelinks-JSON-LD.php

// modify and use within php opening and closing (closing may be not required depending on template)
// add_sitelinks_search_box just a name
// change pub-ABCDEFGH:1234567890 to real value
// PHP_EOL is used to find the newline character in a cross-platform-compatible way
// check your source code to make sure, some other plugin is not echoing a different "target"
// target is Google
// use site url instead of "url": "' . get_site_url() . '/",
// it will decrease the burden of one PHP call
// nginx php5-fpm compatible
// Genesis compatible (use php opening and closing for using with Genesis Simple Hooks)
// not for WP native search
// php opens
function add_sitelinks_search_box (){
    if ( is_front_page() ) {
        echo PHP_EOL . '<script type="application/ld+json">' . PHP_EOL;
        echo '{' . PHP_EOL;
        echo '  "@context": "http://schema.org",' . PHP_EOL;
        echo '  "@type": "WebSite",' . PHP_EOL;
        echo '  "url": "' . get_site_url() . '/",' . PHP_EOL;
        echo '  "potentialAction": {' . PHP_EOL;
        echo '    "@type": "SearchAction",' . PHP_EOL;
        echo '    "target": "https://www.google.com/cse?cx=partner-pub-ABCDEFGH:1234567890&ie=UTF-8&q={search_term_string}&sa=Search",' . PHP_EOL;
        echo '    "query-input": "search_term_string"' . PHP_EOL;
        echo '  }' . PHP_EOL;
        echo '}' . PHP_EOL;
        echo '</script>' . PHP_EOL;
        }
} 
// return the output
add_action( 'wp_footer', 'add_sitelinks_search_box', 10000 );
// php closes