ion-alert

scoped

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.

Presenting

Controller

Inline

When using Ionic with React or Vue, ion-alert can also be placed directly in the template through use of the isOpen property. Note that isOpen must be set to false manually when the alert is dismissed; it will not be updated automatically.

React

import React, { useState } from 'react';
import { IonAlert, IonButton, IonContent } from '@ionic/react';

function Example() {
  const [showAlert, setShowAlert] = useState(false);

  return (
    <IonContent>
      <IonButton onClick={() => setShowAlert(true)}>Click Me</IonButton>
      <IonAlert
        isOpen={showAlert}
        onDidDismiss={() => setShowAlert(false)}
        header="Alert"
        subHeader="Important message"
        message="This is an alert!"
        buttons={['OK']}
      />
    </IonContent>
  );
}

Vue

<template>
  <ion-content>
    <ion-button @click="setOpen(true)">Show Alert</ion-button>
    <ion-alert
      :is-open="isOpenRef"
      header="Alert"
      sub-header="Important message"
      message="This is an alert!"
      :buttons="['OK']"
      @didDismiss="setOpen(false)"
    ></ion-alert>
  </ion-content>
</template>

<script lang="ts">
  import { IonAlert, IonButton, IonContent } from '@ionic/vue';
  import { defineComponent, ref } from 'vue';

  export default defineComponent({
    components: { IonAlert, IonButton },
    setup() {
      const isOpenRef = ref(false);
      const setOpen = (state: boolean) => (isOpenRef.value = state);

      return { isOpenRef, setOpen };
    },
  });
</script>

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.

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

Radio Example

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 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.

/* 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 can be used to style the Alert without needing to target individual elements:

.my-custom-class {
  --background: #e5e5e5;
}

注記

If you are building an Ionic Angular app, the styles need to be added to a global stylesheet file.

Accessibility

Ionic automatically sets the Alert's role to either alertdialog if there are any inputs or buttons included, or alert if there are none.

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.

All ARIA attributes can be manually overwritten by defining custom values in the htmlAttributes property of the Alert.

Interfaces

AlertButton

interface AlertButton {
  text: string;
  role?: 'cancel' | 'destructive' | string;
  cssClass?: string | string[];
  handler?: (value: any) => boolean | void | { [key: string]: any };
}

AlertInput

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

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

animated

Description	If true, the alert will animate.
Attribute	animated
Type	boolean
Default	true

backdropDismiss

Description	If true, the alert will be dismissed when the backdrop is clicked.
Attribute	backdrop-dismiss
Type	boolean
Default	true

buttons

Description	Array of buttons to be added to the alert.
Attribute	undefined
Type	(string ｜ AlertButton)[]
Default	[]

cssClass

Description	Additional classes to apply for custom CSS. If multiple classes are provided they should be separated by spaces.
Attribute	css-class
Type	string ｜ string[] ｜ undefined
Default	undefined

enterAnimation

Description	Animation to use when the alert is presented.
Attribute	undefined
Type	((baseEl: any, opts?: any) => Animation) ｜ undefined
Default	undefined

header

Description	The main title in the heading of the alert.
Attribute	header
Type	string ｜ undefined
Default	undefined

htmlAttributes

Description	Additional attributes to pass to the alert.
Attribute	undefined
Type	undefined ｜ { [key: string]: any; }
Default	undefined

inputs

Description	Array of input to show in the alert.
Attribute	undefined
Type	AlertInput[]
Default	[]

keyboardClose

Description	If true, the keyboard will be automatically dismissed when the overlay is presented.
Attribute	keyboard-close
Type	boolean
Default	true

leaveAnimation

Description	Animation to use when the alert is dismissed.
Attribute	undefined
Type	((baseEl: any, opts?: any) => Animation) ｜ undefined
Default	undefined

message

Description	The main message to be displayed in the alert. message can accept either plaintext or HTML as a string. To display characters normally reserved for HTML, they must be escaped. For example <Ionic> would become &lt;Ionic&gt; For more information: Security Documentation This property accepts custom HTML as a string. Developers who only want to pass plain text can disable the custom HTML functionality by setting innerHTMLTemplatesEnabled: false in the Ionic config.
Attribute	message
Type	IonicSafeString ｜ string ｜ undefined
Default	undefined

mode

Description	The mode determines which platform styles to use.
Attribute	mode
Type	"ios" ｜ "md"
Default	undefined

subHeader

Description	The subtitle in the heading of the alert. Displayed under the title.
Attribute	sub-header
Type	string ｜ undefined
Default	undefined

translucent

Description	If true, the alert will be translucent. Only applies when the mode is "ios" and the device supports backdrop-filter.
Attribute	translucent
Type	boolean
Default	false

Events

Name	Description
ionAlertDidDismiss	Emitted after the alert has dismissed.
ionAlertDidPresent	Emitted after the alert has presented.
ionAlertWillDismiss	Emitted before the alert has dismissed.
ionAlertWillPresent	Emitted before the alert has presented.

Methods

dismiss

Description	Dismiss the alert overlay after it has been presented.
Signature	dismiss(data?: any, role?: string) => Promise<boolean>

onDidDismiss

Description	Returns a promise that resolves when the alert did dismiss.
Signature	onDidDismiss<T = any>() => Promise<OverlayEventDetail<T>>

onWillDismiss

Description	Returns a promise that resolves when the alert will dismiss.
Signature	onWillDismiss<T = any>() => Promise<OverlayEventDetail<T>>

present

Description	Present the alert overlay after it has been created.
Signature	present() => Promise<void>

CSS Shadow Parts

No CSS shadow parts available for this component.

CSS Custom Properties

Name	Description
--backdrop-opacity	Opacity of the backdrop
--background	Background of the alert
--height	Height of the alert
--max-height	Maximum height of the alert
--max-width	Maximum width of the alert
--min-height	Minimum height of the alert
--min-width	Minimum width of the alert
--width	Width of the alert

Slots

No slots available for this component.