Tooltip & Popover Positioning Engine
"Positioning tooltips and popovers is difficult. Popper is here to help!
Given an element, such as a button, and a tooltip element describing it, Popper will automatically put the tooltip in the right place near the button.
It will position any UI element that "pops out" from the flow of your document and floats near a target element. The most common example is a tooltip, but it also includes popovers, drop-downs, and more. All of these can be generically described as a "popper" element."