You can use a plugin named Header and Footer Scripts Inserter to add custom JavaScript to your site. Go to Plugins → Add New on the WordPress menu, and search for Header and Footer Scripts Inserter.
Once installed go to Settings → Header and Footer Scripts Inserter on the WordPress menu. You can add custom JavaScript to either the header or footer of your site.
1 2 3 | <script> // Place your code here </script> |
<script> // Place your code here </script>