Conditional JS scripts for WordPress

conditional-js-scripts.php

// !Tool to easily add a "conditional" data to a script.

if ( ! function_exists('sf_conditional_script') ):
function sf_conditional_script( $script, $condition = 'lt IE 9' ) {
	return $GLOBALS['wp_scripts']->add_data( $script, 'conditional', $condition );
}
endif;


// !Enqueue script(s).

add_action( 'init', 'sf_init_scripts' );

if ( ! function_exists( 'sf_init_scripts' ) ) :
function sf_init_scripts() {
	wp_enqueue_script( 'selectivizr', get_template_directory_uri() . 'polyfills/selectivizr.min.js', array( 'jquery-core' ), '1.0.2', true );
	sf_conditional_script( 'selectivizr' );
}
endif;


// !Add the conditional comments.

add_filter( 'script_loader_tag', 'sf_conditional_scripts', PHP_INT_MAX, 3 );

if ( ! function_exists( 'sf_conditional_scripts' ) ) :
function sf_conditional_scripts( $tag, $handle, $src ) {
	global $wp_scripts;

	if ( $tag && ! $wp_scripts->do_concat && $conditional = $wp_scripts->get_data( $handle, 'conditional' ) ) {
		return "<!--[if $conditional]><script type='text/javascript' src='$src'></script><![endif]-->\n";
	}

	return $tag;
}
endif;