Add preliminary API for registering hooks to run when Blaze intends to insert, move, or remove DOM elements. For example, you can use these hooks to animate nodes as they are inserted, moved, or removed. To use them, you can set the _uihooks property on a container DOM element. _uihooks is an object that can have any subset of the following three properties:
- insertElement: function (node, next): called when Blaze intends to insert the DOM element node before the element next
- moveElement: function (node, next): called when Blaze intends to move the DOM element node before the element next
- removeElement: function (node): called when Blaze intends to remove the DOM element node
Note that when you set one of these functions on a container element, Blaze will not do the actual operation; it's your responsibility to actually insert, move, or remove the node (by calling $(node).remove(), for example).
https://github.com/meteor/meteor/blob/30fb11f1fa0227f1c0ec3eb30b7864ea3b2d210e/History.md