I think that's a nice option if you don't wanna spend your time visiting lots of malls. However, you should be sure that the style's gonna fit you and you have all the measures to understand the size of the clothes (if we speak about the clothes).
I'm a bit confused about buying groceries online as lots of products are not fresh enough and managers may forget about some items. I'm also confused about buying cosmetics and beauty products online unless you're buying the familiar ones.
What about other items I don't mention here, don't hesitate and go buy it online and save your time