WP Editor strips input placeholder attribute

2 comments

1. The list of allowed elements and attributes is stored in the global variable $allowedposttags which is set in wp-includes/kses.php.

   To override it create a simple mu plugin with the following content:

   <?php # -*- coding: utf-8 -*-
   /**
    * Plugin Name: Enable placeholder attribute for input elements in post tags.
    * Version: 2012.07.18
    */
   
   add_action( 'init', 'wpse_54829_register_placeholder' );
   
   
   function wpse_54829_register_placeholder()
   {
       global $allowedposttags;
   
       $default = empty ( $allowedposttags['input'] ) ? array () : $allowedposttags['input'];
       $custom  = array (
           'placeholder' => TRUE,
           'name'        => TRUE,
           'value'       => TRUE,
           'size'        => TRUE,
           'maxlength'   => TRUE,
           'type'        => TRUE,
           'required'    => TRUE
       );
   
       $allowedposttags['input'] = array_merge( $default, $custom );
   }
   

   This post with the content <input placeholder="pass" required /> was created with an author account:

   

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2. You could use a shortcode! 😉

   <?php
   
   // desired output: <input type="text" value="" name="s" style="width: 550px;" placeholder="Search this website..">
   // sc: [text_input name="s" style="width: 550px;" placeholder="Search this website.."]
   
   add_shortcode('text_input','text_input_sc');
   function text_input_sc($atts) {
   
       // modify defaults as you wish
       $defaults = array(
           'id' => null,
           'class' => null,
           'value' => null,
           'name' => null,
           'size' => null,
           'style' => null,
           'placeholder' => null
       );
   
       $args = shortcode_atts($defaults, $atts);
   
       $out = array();
   
       foreach ($args as $attr => $value) {
   
           if ( null !== $value )
               $out[] = $attr.'="'.$value.'"';
   
       }
   
       $out = trim(implode(' ', $out));
   
       if( !empty($out) )
           $out = ' '.$out;
   
       return vsprintf('<input type="text"%s>', $out);
   
   }
   

   Untested, but should definitely work!

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