Source

File: wp-includes/class.wp-scripts.php

public function init() {
		if (
			function_exists( 'is_admin' ) && ! is_admin()
		&&
			function_exists( 'current_theme_supports' ) && ! current_theme_supports( 'html5', 'script' )
		) {
			$this->type_attr = " type='text/javascript'";
		}

		/**
		 * Fires when the WP_Scripts instance is initialized.
		 *
		 * @since 2.6.0
		 *
		 * @param WP_Scripts $this WP_Scripts instance (passed by reference).
		 */
		do_action_ref_array( 'wp_default_scripts', array( &$this ) );
	}