While the ideal customer comes in, finds what he wants, buys it, and leaves, this is not always the case with online shopping. The average customer may make a few store visits before completing a purchase. While a majority of these visits are always on the same device, a subset of shoppers tend to device hop since nearly everyone owns a phone in addition to either a computer or a tablet.
For logged in customers
For customers with registered accounts, product browsing data, cart items (see best practice #106), and purchase history should be synced across all of their devices. This provides for a seamless experience when a customer shifts from one device to another.
Since browsers like Google Chrome already sync user data like passwords, history, and form data across multiple devices, shoppers already come to your store with the expectation that all their data will be synchronized across all devices.
Let’s take Jonah as an example. He has been working from home for a while and feels that his physical health could use some improvement. He decides to buy a treadmill desk so he can exercise while still keeping up with work.
He comes to your site and browses a couple of models on his phone while lying in bed. He zeroes in two or three models that he feels would be ideal but his wife asks for a back rub so the hunt has to be abandoned.
The next day while Jonah is sitting at his desk in the home office, he remembers the hunt for the treadmill desk so opens up a new tab on his work computer and logs back in to your site. If his product browsing history is synced, he’ll just go to the recently viewed category, and complete his purchase. Otherwise, he may have to begin the product search afresh.
He could always whip out his phone and continue browsing from there but he has had all non vital functions disabled by a productivity app so he could focus on work. That’s a lost sale right there. Even if he remembers the treadmill desk he wanted, Jonah might be so pissed that he decides to take his business elsewhere just for spite.
For guest users
Currently there is no way to sync the data of guest users across multiple devices without violating a ton of privacy laws so the best you can do is email them their cart contents.