How to Auto populated questions while user typing

In MongoDb you can use the regular expressions in JavaScript to capture the objects. This brings the features similar to SQL Server's LIKE expression and lets you search for the elements based on a regular expression.

Taken from here, https://stackoverflow.com/questions/3305561/how-to-query-mongodb-with-like,

db.users.find({name: /^h/}) //like 'h%'

So that is how you can do this, one thing to notice here is that you should consider applying indexing to the column, otherwise it will be a really slow process, making the engine to scan through the entire table to find an output.