Twenty Seventeen Theme - Better Version Control

asset-helpers.php

<?php
/**
 * Asset Loaders and Helpers for Twenty Seventeen Theme
 *
 * @since       1.0.0
 * @author      hellofromTonya
 * @link        https://KnowTheCode.io
 * @license     GNU-2.0+
 */

add_action( 'wp_enqueue_scripts', 'twentyseventeen_scripts' );
/**
 * Enqueue scripts and styles.
 */
function twentyseventeen_scripts() {
	$version_number = get_theme_version();

	// Add custom fonts, used in the main stylesheet.
	wp_enqueue_style( 'twentyseventeen-fonts', twentyseventeen_fonts_url(), array(), null );

	// Theme stylesheet.
	wp_enqueue_style( 'twentyseventeen-style', get_stylesheet_uri(), array(), $version_number );

	// Load the dark colorscheme.
	if ( 'dark' === get_theme_mod( 'colorscheme', 'light' ) || is_customize_preview() ) {
		wp_enqueue_style( 'twentyseventeen-colors-dark', get_theme_file_uri( '/assets/css/colors-dark.css' ), array( 'twentyseventeen-style' ), $version_number );
	}

	// Load the Internet Explorer 9 specific stylesheet, to fix display issues in the Customizer.
	if ( is_customize_preview() ) {
		wp_enqueue_style( 'twentyseventeen-ie9', get_theme_file_uri( '/assets/css/ie9.css' ), array( 'twentyseventeen-style' ), $version_number );
		wp_style_add_data( 'twentyseventeen-ie9', 'conditional', 'IE 9' );
	}

	// Load the Internet Explorer 8 specific stylesheet.
	wp_enqueue_style( 'twentyseventeen-ie8', get_theme_file_uri( '/assets/css/ie8.css' ), array( 'twentyseventeen-style' ), '1.0' );
	wp_style_add_data( 'twentyseventeen-ie8', 'conditional', 'lt IE 9' );

	// Load the html5 shiv.
	wp_enqueue_script( 'html5', get_theme_file_uri( '/assets/js/html5.js' ), array(), '3.7.3' );
	wp_script_add_data( 'html5', 'conditional', 'lt IE 9' );

	wp_enqueue_script( 'twentyseventeen-skip-link-focus-fix', get_theme_file_uri( '/assets/js/skip-link-focus-fix.js' ), array(), '1.0', true );

	$twentyseventeen_l10n = array(
		'quote'          => twentyseventeen_get_svg( array( 'icon' => 'quote-right' ) ),
	);

	if ( has_nav_menu( 'top' ) ) {
		wp_enqueue_script( 'twentyseventeen-navigation', get_theme_file_uri( '/assets/js/navigation.js' ), array( 'jquery' ), '1.0', true );
		$twentyseventeen_l10n['expand']         = __( 'Expand child menu', 'twentyseventeen' );
		$twentyseventeen_l10n['collapse']       = __( 'Collapse child menu', 'twentyseventeen' );
		$twentyseventeen_l10n['icon']           = twentyseventeen_get_svg( array( 'icon' => 'angle-down', 'fallback' => true ) );
	}

	wp_enqueue_script( 'twentyseventeen-global', get_theme_file_uri( '/assets/js/global.js' ), array( 'jquery' ), '1.0', true );

	wp_enqueue_script( 'jquery-scrollto', get_theme_file_uri( '/assets/js/jquery.scrollTo.js' ), array( 'jquery' ), '2.1.2', true );

	wp_localize_script( 'twentyseventeen-skip-link-focus-fix', 'twentyseventeenScreenReaderText', $twentyseventeen_l10n );

	if ( is_singular() && comments_open() && get_option( 'thread_comments' ) ) {
		wp_enqueue_script( 'comment-reply' );
	}
}

function get_theme_version() {

	$version_number = get_asset_current_version_number( get_stylesheet_directory() . '/style.css' );
	if ( $version_number !== false ) {
		return $version_number;
	}

	$theme = wp_get_theme();

	return $theme->get('Version');

//	if ( site_is_in_debug_mode() ) {
//		$stylesheet = get_stylesheet_directory() . '/style.css';
//
//		return filemtime( $stylesheet );
//	}
//
//	return '1.3';

}

function get_asset_current_version_number( $asset_file ) {
	if ( ! site_is_in_debug_mode() ) {
		return false;
	}

	return filemtime( $asset_file );
}

/**
 * Checks if the site is in development/debug mode.
 *
 * @since 1.0.0
 *
 * @return bool
 */
function site_is_in_debug_mode() {
	if ( ! defined( 'SCRIPT_DEBUG' ) ) {
		return false;
	}

	return ( (bool) SCRIPT_DEBUG === true );
}

This gist is for the Better Asset Versioning hands-on coding lab, episode 4 - Forget Hard Coding Version Number. Put this file into inc/support/asset-helpers.php.