Can you explain the significance of this code snippet 'true <=> false'?

Today I came across this piece of code: true <=> false. I'm a bit confused by it and don't really understand how it works.

If anyone could shed some light on this expression for me, I would greatly appreciate it.

For reference, this code snippet was found in the control page animation section of an ionic 4 project.

export const FeedOut = trigger('state', [
  state('false', hiddenStyle),
  state('true', showStyle),
  transition('true <=> false', animate('300ms ease-in')),
  transition(':leave', animate(400, hiddenStyle)),
]);

Thanks in advance!

javascriptangulartypescript

Answer №1

The following code snippet showcases how transition animations are defined in Angular. A trigger named 'state' is set up to manage two states; referred to as 'false' and 'true'. It's important to note that these state names are arbitrary and can be customized for clarity, such as using 'hiddenState' and 'shownState'.

The transitions between the states are then specified, indicating seamless movement from 'false' to 'true' or vice versa.

In your HTML code, you might encounter [@state]="...". If this section mentions 'false' and/or 'true', updating them to new state names is advised. To prevent confusion, consider changing 'state' to 'mytrigger' throughout both the .ts file and any associated .html files.

Edit: It appears that Angular now processes booleans directly, allowing the use of 'true' and 'false' as state names without conversion to strings, simplifying evaluation within the HTML template

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