functions.php

add_action( 'wp_enqueue_scripts', 'my_strength_meter_localize_script' );
function my_strength_meter_localize_script() {
    wp_localize_script( 'password-strength-meter', 'pwsL10n', array(
        'empty'    => __( 'But... it\'s empty!', 'theme-domain' ),
        'short'    => __( 'Too short!', 'theme-domain' ),
        'bad'      => __( 'Not even close!', 'theme-domain' ),
        'good'     => __( 'You are getting closer...', 'theme-domain' ),
        'strong'   => __( 'Now, that\'s a password!', 'theme-domain' ),
        'mismatch' => __( 'They are completely different, come on!', 'theme-domain' )
    ) );
}