WordPress Customizer Live Preview / Save / Sanitize Example

wp_customizer_lpss_example.php

<?php
$wp_customize->add_setting( 'setting_id', array(
  'type' => 'theme_mod', // or 'option'
  'capability' => 'edit_theme_options',
  'theme_supports' => '', // Rarely needed
  'default' => '',
  'transport' => 'refresh', // or postMessage
  'sanitize_callback' => '',
  'sanitize_js_callback' => '', // Essentially converts to JSON
  ) );
?>