Html.Keyed

A keyed node helps optimize cases where children are getting added, moved, removed, etc. Common examples include:

  • The user can delete items from a list.
  • The user can create new items in a list.
  • You can sort a list based on name or date or whatever.

When you use a keyed node, every child is paired with a string identifier. This makes it possible for the underlying diffing algorithm to reuse nodes more efficiently.

Keyed Nodes

node :
String
-> Array (Attribute msg)
-> Array { key : String, node : Html msg }
-> Html msg

Works just like Html.node, but you add a unique identifier to each child node. You want this when you have a list of nodes that is changing: adding nodes, removing nodes, etc. In these cases, the unique identifiers help make the DOM modifications more efficient.

Commonly Keyed Nodes

ol :
Array (Attribute msg)
-> Array { key : String, node : Html msg }
-> Html msg
ul :
Array (Attribute msg)
-> Array { key : String, node : Html msg }
-> Html msg