wordpress functions.php

function my_acf_load_field( $field ) {	
	if ( ! empty ( $_GET[$field['name']] )) {
		$field['default_value'] = $_GET[$field['name']];
    }
    return $field;
}
add_filter('acf/load_field', 'my_acf_load_field');

remove_filter( 'the_content', 'wpautop' );

function my_admin_script(){
    if(get_post_type() === 'post'){
		// 注意 JS内でダブルクオーテーションを使うとエラーになる
        echo "<script>
				document.addEventListener('DOMContentLoaded', function(event) {
					const element = document.getElementById('acf-field-isbn'); 
					if (element.value!=='') {
						let a = document.createElement('a');
						a.innerText = 'hontoで開く';
						a.target = '_blank';
						a.style = 'display:inline-block;margin-top:10px;';
						a.href = 'http://honto.jp/redirect.html?bookno='+element.value.slice(0, -1);
						element.parentNode.insertBefore(a, element.nextSibling); 
					}
				});
        </script>".PHP_EOL;
    }
}
add_action("admin_print_scripts-post-new.php", "my_admin_script");

// コンテンツエディタのfontをリセット
function my_admin_style() {
  echo '<style>
	.wp-editor-area {
		font-family: "" !important;
	}
  </style>'.PHP_EOL;
}
add_action('admin_print_styles', 'my_admin_style');