Hi @mahima,
I assume snippet.js is the JS you are injecting in the UI, And you are trying the access the settings & values from the plugin settings page in the JS.
Unfortunately you cannot do this directly, The plugin settings and their values are not exported to the UI layer.
You have to write a Java class that exposes your setting as API. And, you have to make an API call to the backend and retrieve your settings.
If you are looking for references I would recommend you to check-out one of my Plugin - IdentityIQ Announcement Plugin