A Toast is a subtle notification commonly used in modern applications. It can be used to provide feedback about an operation or to display a system message. The toast appears on top of the app's content, and can be dismissed by the app to resume user interaction with the app.
The isOpen property on ion-toast allows developers to control the presentation state of the toast from their application state. This means when isOpen is set to true the toast will be presented and when isOpen is set to false the toast will be dismissed.
isOpen uses a one-way data binding, meaning it will not automatically be set to false when the toast is dismissed. Developers should listen for the ionToastDidDismiss or didDismiss event and set isOpen to false. The reason for this is it prevents the internals of ion-toast from being tightly coupled with the state of the application. With a one way data binding, the toast only needs to concern itself with the boolean value that the reactive variable provides. With a two way data binding, the toast needs to concern itself with both the boolean value as well as the existence of the reactive variable itself. This can lead to non-deterministic behaviors and make applications harder to debug.
The toast can be dismissed automatically after a specific amount of time by passing the number of milliseconds to display it in the duration of the toast options. If a button with a role of "cancel" is added, then that button will dismiss the toast. To dismiss the toast after creation, call the dismiss() method on the instance.
The following example demonstrates how to use the buttons property to add a button that automatically dismisses the toast when clicked, as well as how to collect the role of the dismiss event.
Toasts can be positioned at the top, bottom or middle of the viewport. The position can be passed upon creation. The possible values are top, bottom and middle. If the position is not specified, the toast will be displayed at the bottom of the viewport.
An icon can be added next to the content inside of the toast. In general, icons in toasts should be used to add additional style or context, not to grab the user's attention or elevate the priority of the toast. If you wish to convey a higher priority message to the user or guarantee a response, we recommend using an Alert instead.
Toasts are intended to be subtle notifications and are not intended to interrupt the user. User interaction should not be required to dismiss the toast. As a result, focus is not automatically moved to a toast when one is presented.
ion-toast has aria-live="polite" and aria-atomic="true" set by default.
aria-live causes screen readers to announce the content of the toast when it is updated. However, since the attribute is set to 'polite', screen readers generally do not interrupt the current task. Developers can customize this behavior by using the htmlAttributes property to set aria-live to 'assertive'. This will cause screen readers to immediately notify the user when a toast is updated, potentially interrupting any previous updates.
aria-atomic="true" is set to ensure that the entire toast is announced as a single unit. This is useful when dynamically updating the content of the toast as it prevents screen readers from announcing only the content that has changed.
While this is not a complete list, here are some guidelines to follow when using toasts.
Do not require user interaction to dismiss toasts. For example, having a "Dismiss" button in the toast is fine, but the toast should also automatically dismiss on its own after a timeout period. If you need user interaction for a notification, consider using ion-alert instead.
Avoid opening multiple toasts in quick succession. If aria-live is set to 'assertive', screen readers may interrupt the reading of the current task to announce the new toast, causing the context of the previous toast to be lost.
For toasts with long messages, consider adjusting the duration property to allow users enough time to read the content of the toast.
The color to use from your application's color palette. Default options are: "primary", "secondary", "tertiary", "success", "warning", "danger", "light", "medium", and "dark". For more information on colors, see theming.