Multiple checkbox customizer control

custom-control.js

jQuery( document ).ready( function() {

    /* === Checkbox Multiple Control === */

    jQuery( '.customize-control-checkbox-multiple input[type="checkbox"]' ).on( 'change', function() {

            checkbox_values = jQuery( this ).parents( '.customize-control' ).find( 'input[type="checkbox"]:checked' ).map(
                function() {
                    return this.value;
                }
            ).get().join( ',' );

            jQuery( this ).parents( '.customize-control' ).find( 'input[type="hidden"]' ).val( checkbox_values ).trigger( 'change' );
        }
    );

} ); // jQuery( document ).ready

multiple-checkbox-control-sanitize.php

<?php

/**
 * Sanitize the Multiple checkbox values.
 *
 * @param string $values Values.
 * @return array Checked values.
 */
function sanitize_multiple_checkbox( $values ) {

	$multi_values = ! is_array( $values ) ? explode( ',', $values ) : $values;

    return !empty( $multi_values ) ? array_map( 'sanitize_text_field', $multi_values ) : array();
}

multiple-checkbox-control-usage.php

<?php
$wp_customize->add_setting( 'pfun_recaptcha_places', array(
		'default'           => array('register', 'submit', 'pass', 'reset'),
		'sanitize_callback' => 'sanitize_multiple_checkbox',
		'transport'         => 'postMessage',
	) );
$wp_customize->add_control( new PFUN_Customize_Control_Checkbox_Multiple( $wp_customize, 'pfun_recaptcha_places', array(
		'label'    => __( 'Form Security', 'pfun' ),
		'description'    => __( 'Select where you want to display Security Question/Answer for anti-spapm.', 'pfun' ),
		'section'  => 'pfun_general_section',
		'choices'  => array(
			'login' 	=> __( 'Login Form', 'pfun' ),
			'register' 	=> __( 'Registration Form', 'pfun' ),
			'submit' 	=> __( 'Post Submit Form', 'pfun' ),
			'pass' 		=> __( 'Change Password Form', 'pfun' ),
			'reset' 	=> __( 'Reset Password Form', 'pfun' ),
			),
		'priority' => 2,
	) ) );

multiple-checkbox-control.php

<?php

/**
 * Multiple checkbox customize control class.
 * URL: http://wpsites.org/multiple-checkbox-customizer-control-10868/
 *
 */
class PFUN_Customize_Control_Checkbox_Multiple extends WP_Customize_Control {

    /**
     * The type of customize control being rendered.
     *
     * @since  1.0.0
     * @access public
     * @var    string
     */
    public $type = 'checkbox-multiple';

    /**
     * Enqueue scripts/styles.
     *
     * @since  1.0.0
     * @access public
     * @return void
     */
    public function enqueue() {
        wp_enqueue_script( 'pfun-customize-controls', trailingslashit( get_template_directory_uri() ) . 'js/customize-controls.js', array( 'jquery' ), null, true );
    }

    /**
     * Displays the control content.
     *
     * @since  1.0.0
     * @access public
     * @return void
     */
    public function render_content() {

        if ( empty( $this->choices ) )
            return; ?>

        <?php if ( !empty( $this->label ) ) : ?>
            <span class="customize-control-title"><?php echo esc_html( $this->label ); ?></span>
        <?php endif; ?>

        <?php if ( !empty( $this->description ) ) : ?>
            <span class="description customize-control-description"><?php echo $this->description; ?></span>
        <?php endif; ?>

        <?php $multi_values = !is_array( $this->value() ) ? explode( ',', $this->value() ) : $this->value(); ?>

        <ul>
            <?php foreach ( $this->choices as $value => $label ) : ?>

                <li>
                    <label>
                        <input type="checkbox" value="<?php echo esc_attr( $value ); ?>" <?php checked( in_array( $value, $multi_values ) ); ?> /> 
                        <?php echo esc_html( $label ); ?>
                    </label>
                </li>

            <?php endforeach; ?>
        </ul>

        <input type="hidden" <?php $this->link(); ?> value="<?php echo esc_attr( implode( ',', $multi_values ) ); ?>" />
    <?php }
}