<?php
function understrap_customize_register( $wp_customize ) {
	$wp_customize->get_setting('blogname')->transport         = 'postMessage';
	$wp_customize->get_setting('blogdescription')->transport  = 'postMessage';
	$wp_customize->get_setting('header_textcolor')->transport = 'postMessage';

}
add_action('customize_register', 'understrap_customize_register');

function understrap_customize_preview_js() {
	wp_enqueue_script('understrap_customizer', get_template_directory_uri() . '/js/customizer.js', array('customize-preview'), '20130508', true);
}
add_action('customize_preview_init', 'understrap_customize_preview_js');