Delay

Elm utilities to trigger updates after a delay

example: https://andrewmacmurray.github.io/elm-delay/

Why?

Sometimes you need to trigger updates after a period of time (i.e. to wait for a css transition or animation to complete) or maybe you need to chain a sequence of these updates (for more complex states).

This library provides utilities to express this more tidily.

How?

Send a single delayed Msg

To trigger a single update after a period of time pass Delay.after as a command to the elm runtime:

FirstMessage ->
    model ! [ Delay.after 500 millisecond SecondMessage ]

After triggering FirstMessage, 500ms later update will be called with SecondMessage

Send a sequence of delayed Msgs

Trigger ->
    model
        ! [ Delay.sequence
                [ ( 1000, millisecond, FirstMessage )
                , ( 2000, millisecond, SecondMessage )
                , ( 1000, millisecond, ThirdMessage )
                ]
          ]

by sending a Trigger Msg:

• after 1000ms update will be called with FirstMessage
• then after 2000ms update will be called with SecondMessage
• then after 1000ms update will be called with ThirdMessage

As a convenience if you'd only like to start a sequence if the model is in a particular shape you can use Delay.sequenceIf

Trigger ->
    model
        ! [ Delay.sequenceIf (not model.updating)
                [ ( 1000, millisecond, FirstMessage )
                , ( 2000, millisecond, SecondMessage )
                , ( 1000, millisecond, ThirdMessage )
                ]
          ]

If you'd like all the steps to have the same unit of time, use the Delay.withUnit helper

Trigger ->
    model
        ! [ Delay.sequence <|
                Delay.withUnit millisecond
                    [ ( 1000, FirstMessage )
                    , ( 2000, SecondMessage )
                    , ( 1000, ThirdMessage )
                    ]
          ]