Stripe.js is a secure option since it ensures that the credit card information doesn't hit your server, thereby minimizing the scope of your PCI compliance.
There are two ways to implement Stripe.js:
1) Embed Stripe’s form into your checkout page so that your customer can enter both personal and card information. Here's a tutorial on this.
2) Use Stripe’s pop-up form so that your customer enters personal information in your website and card information on the pop-up window that Stripe provides. Here's a tutorial on this.
Either way, the information will be passed directly to Stripe.