---
title: "ion-alert"
---
import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';
import Props from '@ionic-internal/component-api/v8/alert/props.md';
import Events from '@ionic-internal/component-api/v8/alert/events.md';
import Methods from '@ionic-internal/component-api/v8/alert/methods.md';
import Parts from '@ionic-internal/component-api/v8/alert/parts.md';
import CustomProps from '@ionic-internal/component-api/v8/alert/custom-props.mdx';
import Slots from '@ionic-internal/component-api/v8/alert/slots.md';
ion-alert: Ionic Alert Buttons with Custom Message Prompts
import EncapsulationPill from '@components/page/api/EncapsulationPill';
An Alert is a dialog that presents users with information or collects information from the user using inputs. An alert appears on top of the app's content, and must be manually dismissed by the user before they can resume interaction with the app. It can also optionally have a `header`, `subHeader` and `message`.
## Inline Alerts (Recommended)
`ion-alert` can be used by writing the component directly in your template. This reduces the number of handlers you need to wire up in order to present the Alert.
import Trigger from '@site/static/usage/v8/alert/presenting/trigger/index.md';
### Using `isOpen`
The `isOpen` property on `ion-alert` allows developers to control the presentation state of the Alert from their application state. This means when `isOpen` is set to `true` the Alert will be presented, and when `isOpen` is set to `false` the Alert will be dismissed.
`isOpen` uses a one-way data binding, meaning it will not automatically be set to `false` when the Alert is dismissed. Developers should listen for the `ionAlertDidDismiss` or `didDismiss` event and set `isOpen` to `false`. The reason for this is it prevents the internals of `ion-alert` from being tightly coupled with the state of the application. With a one way data binding, the Alert only needs to concern itself with the boolean value that the reactive variable provides. With a two way data binding, the Alert 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.
import IsOpen from '@site/static/usage/v8/alert/presenting/isOpen/index.md';
## Controller Alerts
The `alertController` can be used in situations where more control is needed over when the Alert is presented and dismissed.
import Controller from '@site/static/usage/v8/alert/presenting/controller/index.md';
## Buttons
In the array of `buttons`, each button includes properties for its `text`, and optionally a `handler`. If a handler returns `false` then the alert will not automatically be dismissed when the button is clicked. All buttons will show up in the order they have been added to the `buttons` array from left to right. Note: The right most button (the last one in the array) is the main button.
Optionally, a `role` property can be added to a button, such as `cancel`. If a `cancel` role is on one of the buttons, then if the alert is dismissed by tapping the backdrop, then it will fire the handler from the button with a cancel role.
import Buttons from '@site/static/usage/v8/alert/buttons/index.md';
## Inputs
Alerts can also include several different inputs whose data can be passed back to the app. Inputs can be used as a simple way to prompt users for information. Radios, checkboxes and text inputs are all accepted, but they cannot be mixed. For example, an alert could have all radio button inputs, or all checkbox inputs, but the same alert cannot mix radio and checkbox inputs. Do note however, different types of "text" inputs can be mixed, such as `url`, `email`, `text`, `textarea` etc. If you require a complex form UI which doesn't fit within the guidelines of an alert then we recommend building the form within a modal instead.
### Text Inputs Example
import TextInputs from '@site/static/usage/v8/alert/inputs/text-inputs/index.md';
### Radio Example
import Radios from '@site/static/usage/v8/alert/inputs/radios/index.md';
## Customization
Alert uses scoped encapsulation, which means it will automatically scope its CSS by appending each of the styles with an additional class at runtime. Overriding scoped selectors in CSS requires a [higher specificity](https://developer.mozilla.org/en-US/docs/Web/CSS/Specificity) selector.
We recommend passing a custom class to `cssClass` in the `create` method and using that to add custom styles to the host and inner elements. This property can also accept multiple classes separated by spaces.
```css
/* DOES NOT WORK - not specific enough */
.alert-wrapper {
background: #e5e5e5;
}
/* Works - pass "my-custom-class" in cssClass to increase specificity */
.my-custom-class .alert-wrapper {
background: #e5e5e5;
}
```
Any of the defined [CSS Custom Properties](#css-custom-properties) can be used to style the Alert without needing to target individual elements:
```css
.my-custom-class {
--background: #e5e5e5;
}
```
import Customization from '@site/static/usage/v8/alert/customization/index.md';
:::note
If you are building an Ionic Angular app, the styles need to be added to a global stylesheet file.
:::
## Accessibility
### Screen Readers
Alerts set aria properties in order to be [accessible](../reference/glossary#a11y) to screen readers, but these properties can be overridden if they aren't descriptive enough or don't align with how the alert is being used in an app.
#### Role
Ionic automatically sets the Alert's `role` to either [`alertdialog`](https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Roles/alertdialog_role) if there are any inputs or buttons included, or [`alert`](https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Roles/alert_role) if there are none.
#### Alert Description
If the `header` property is defined for the Alert, the `aria-labelledby` attribute will be automatically set to the header's ID. The `subHeader` element will be used as a fallback if `header` is not defined. Similarly, the `aria-describedby` attribute will be automatically set to the ID of the `message` element if that property is defined.
It is strongly recommended that your Alert have a `message`, as well as either a `header` or `subHeader`, in order to align with the ARIA spec. If you choose not to include a `header` or `subHeader`, an alternative is to provide a descriptive `aria-label` using the `htmlAttributes` property.
```javascript
const alert = await this.alertController.create({
message: 'This is an alert with custom aria attributes.',
htmlAttributes: {
'aria-label': 'alert dialog',
},
});
```
```javascript
const alert = await this.alertController.create({
message: 'This is an alert with custom aria attributes.',
htmlAttributes: {
'aria-label': 'alert dialog',
},
});
```
```javascript
useIonAlert({
message: 'This is an alert with custom aria attributes.',
htmlAttributes: {
'aria-label': 'alert dialog',
},
});
```
```javascript
const alert = await alertController.create({
message: 'This is an alert with custom aria attributes.',
htmlAttributes: {
'aria-label': 'alert dialog',
},
});
```
All ARIA attributes can be manually overwritten by defining custom values in the `htmlAttributes` property of the Alert.
#### Alert Buttons Description
Buttons containing text will be read by a screen reader. If a description other than the existing text is desired, a label can be set on the button by passing `aria-label` to the `htmlAttributes` property on the button.
```javascript
const alert = await this.alertController.create({
header: 'Header',
buttons: [
{
text: 'Exit',
htmlAttributes: {
'aria-label': 'close',
},
},
],
});
```
```javascript
const alert = await this.alertController.create({
header: 'Header',
buttons: [
{
text: 'Exit',
htmlAttributes: {
'aria-label': 'close',
},
},
],
});
```
```javascript
useIonAlert({
header: 'Header',
buttons: [
{
text: 'Exit',
htmlAttributes: {
'aria-label': 'close',
},
},
],
});
```
```javascript
const alert = await alertController.create({
header: 'Header',
buttons: [
{
text: 'Exit',
htmlAttributes: {
'aria-label': 'close',
},
},
],
});
```
## Interfaces
### AlertButton
```typescript
type AlertButtonOverlayHandler = boolean | void | { [key: string]: any };
interface AlertButton {
text: string;
role?: 'cancel' | 'destructive' | string;
cssClass?: string | string[];
id?: string;
htmlAttributes?: { [key: string]: any };
handler?: (value: any) => AlertButtonOverlayHandler | Promise;
}
```
### AlertInput
```typescript
interface AlertInput {
type?: TextFieldTypes | 'checkbox' | 'radio' | 'textarea';
name?: string;
placeholder?: string;
value?: any;
/**
* The label text to display next to the input, if the input type is `radio` or `checkbox`.
*/
label?: string;
checked?: boolean;
disabled?: boolean;
id?: string;
handler?: (input: AlertInput) => void;
min?: string | number;
max?: string | number;
cssClass?: string | string[];
attributes?: { [key: string]: any };
tabindex?: number;
}
```
### AlertOptions
```typescript
interface AlertOptions {
header?: string;
subHeader?: string;
message?: string | IonicSafeString;
cssClass?: string | string[];
inputs?: AlertInput[];
buttons?: (AlertButton | string)[];
backdropDismiss?: boolean;
translucent?: boolean;
animated?: boolean;
htmlAttributes?: { [key: string]: any };
mode?: Mode;
keyboardClose?: boolean;
id?: string;
enterAnimation?: AnimationBuilder;
leaveAnimation?: AnimationBuilder;
}
```
## Properties
## Events
## Methods
## CSS Shadow Parts
## CSS Custom Properties
## Slots