Enqueue the script or style using wp_enqueue_script() or wp_enqueue_style() code example

Example 1: enqueue wordpress

function wpdocs_theme_name_scripts() {
    wp_enqueue_style( 'style-name', get_stylesheet_uri() ); /* enqueues style.css */
    /* if you want to enqueue other styles use: */
    /* wp_enqueue_style( 'style-name', get_template_directory_uri() . '/css/your-style-name.css' ); */
    wp_enqueue_script( 'script-name', get_template_directory_uri() . '/js/example.js', array(), '1.0.0', true );
}
add_action( 'wp_enqueue_scripts', 'wpdocs_theme_name_scripts' );

Example 2: wordpress include javascript file

function jquery_tabify() {
    wp_enqueue_script(
        'jquery-tabify',
        'http://site.com/jquery.tabify.js',
        array( 'jquery' )
    );
}
add_action( 'wp_enqueue_scripts', 'jquery_tabify' );