256 lines
9 KiB
Markdown
256 lines
9 KiB
Markdown
# Checkbox Group >> Use Cases ||20
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```js script
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import { html } from '@mdjs/mdjs-preview';
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import '@lion/ui/define/lion-checkbox-group.js';
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import '@lion/ui/define/lion-checkbox.js';
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```
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## Model value
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The `modelValue` of a `lion-checkbox-group` is an array containing the `choiceValues` of the `lion-checkbox` elements that have been checked.
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Given the scientists example above, say that we were to select the first and last options
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(Archimedes & Marie Curie).
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Then the `modelValue` of the `lion-checkbox-group` will look as follows:
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```js
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const groupElement = [parent].querySelector('lion-checkbox-group');
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groupElement.modelValue;
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=> ["Archimedes", "Marie Curie"];
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```
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## The `name` attribute
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The `name` attribute of a `lion-checkbox-group` automatically gets assigned to its `lion-checkbox` children. You can also specify names for the `lion-checkbox` elements, but if this name is different from the name assigned to `lion-checkbox-group`, then an exception will be thrown.
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Our recommendation would be to set the `name` attribute only on the `lion-checkbox-group` and not on the `lion-checkbox` elements.
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## Example
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```html
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<lion-checkbox-group
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name="scientists[]"
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label="Favorite scientists"
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>
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<lion-checkbox label="Archimedes" .choiceValue=${'Archimedes'}></lion-checkbox>
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<lion-checkbox label="Francis Bacon" .choiceValue=${'Francis Bacon'}></lion-checkbox>
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<lion-checkbox label="Marie Curie" .choiceValue=${'Marie Curie'}></lion-checkbox>
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</lion-checkbox-group>
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```
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## Pre-select
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You can pre-select options by targeting the `modelValue` object of the option and setting the `checked` property to `true`.
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```js preview-story
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export const preselect = () => html`
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<lion-checkbox-group name="scientists" label="Favorite scientists">
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<lion-checkbox label="Archimedes" .choiceValue=${'Archimedes'}></lion-checkbox>
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<lion-checkbox label="Francis Bacon" .choiceValue=${'Francis Bacon'} checked></lion-checkbox>
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<lion-checkbox
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label="Marie Curie"
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.modelValue=${{ value: 'Marie Curie', checked: true }}
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></lion-checkbox>
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</lion-checkbox-group>
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`;
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```
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## Disabled
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You can disable the entire group by setting the `disabled` attribute on the `<lion-checkbox-group>`.
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```js preview-story
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export const disabled = () => html`
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<lion-checkbox-group name="scientists[]" label="Favorite scientists" disabled>
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<lion-checkbox label="Archimedes" .choiceValue=${'Archimedes'}></lion-checkbox>
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<lion-checkbox label="Francis Bacon" .choiceValue=${'Francis Bacon'}></lion-checkbox>
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<lion-checkbox
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label="Marie Curie"
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.modelValue=${{ value: 'Marie Curie', checked: true }}
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></lion-checkbox>
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</lion-checkbox-group>
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`;
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```
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## Label
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You can use `slot="label"` instead of the `label` attribute for defining more complex labels, such as containing screen reader only text or an anchor.
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```js preview-story
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export const label = () => html`
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<lion-checkbox-group name="scientists[]" label="Favorite scientists">
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<lion-checkbox .choiceValue=${'Archimedes'}>
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<label slot="label"
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><a href="https://wikipedia.org/wiki/Archimedes" target="_blank">Archimedes</a></label
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>
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</lion-checkbox>
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<lion-checkbox .choiceValue=${'Francis Bacon'}>
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<label slot="label"
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><a href="https://wikipedia.org/wiki/Francis_Bacon" target="_blank">Francis Bacon</a></label
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>
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</lion-checkbox>
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<lion-checkbox .choiceValue=${'Marie Curie'}>
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<label slot="label"
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><a href="https://wikipedia.org/wiki/Marie_Curie" target="_blank">Marie Curie</a></label
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>
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</lion-checkbox>
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</lion-checkbox-group>
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`;
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```
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## Help text
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You can add help text on each checkbox with `help-text` attribute on the `<lion-checkbox>`.
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```js preview-story
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export const helpText = () => html`
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<lion-checkbox-group name="scientists[]" label="Favorite scientists">
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<lion-checkbox
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label="Archimedes"
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.choiceValue=${'Archimedes'}
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help-text="Archimedes of Syracuse was a Greek mathematician, physicist, engineer, inventor, and astronomer"
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></lion-checkbox>
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<lion-checkbox
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label="Francis Bacon"
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.choiceValue=${'Francis Bacon'}
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help-text="Francis Bacon, 1st Viscount St Alban also known as Lord Verulam, was an English philosopher and statesman who served as Attorney General and as Lord Chancellor of England"
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></lion-checkbox>
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<lion-checkbox
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label="Marie Curie"
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.choiceValue=${'Marie Curie'}
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help-text="Marie Skłodowska Curie born Maria Salomea Skłodowska, was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity"
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></lion-checkbox>
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</lion-checkbox-group>
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`;
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```
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## Event
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You can listen to the `model-value-changed` event whenever the value of the checkbox group is changed.
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```js preview-story
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export const event = ({ shadowRoot }) => html`
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<lion-checkbox-group
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name="scientists[]"
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label="Favorite scientists"
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@model-value-changed=${ev =>
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(ev.target.parentElement.querySelector('#selectedDinosaur').innerText = JSON.stringify(
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ev.target.modelValue,
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null,
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4,
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))}
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>
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<lion-checkbox label="Archimedes" .choiceValue=${'Archimedes'}></lion-checkbox>
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<lion-checkbox label="Francis Bacon" .choiceValue=${'Francis Bacon'}></lion-checkbox>
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<lion-checkbox label="Marie Curie" .choiceValue=${'Marie Curie'}></lion-checkbox>
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</lion-checkbox-group>
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<br />
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<span>Selected scientists: <strong id="selectedDinosaur">N/A</strong></span>
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`;
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```
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## Indeterminate
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A `checkbox-indeterminate`'s value is neither true nor false, but is instead indeterminate, meaning that its state cannot be determined or stated in pure binary terms, based on it's `checkbox` children.
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```js preview-story
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export const indeterminateSiblings = () => html`
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<lion-checkbox-group name="scientists[]" label="Favorite scientists">
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<lion-checkbox-indeterminate label="Old Greek scientists">
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<lion-checkbox
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slot="checkbox"
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label="Archimedes"
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.choiceValue=${'Archimedes'}
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></lion-checkbox>
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<lion-checkbox slot="checkbox" label="Plato" .choiceValue=${'Plato'}></lion-checkbox>
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<lion-checkbox
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slot="checkbox"
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label="Pythagoras"
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.choiceValue=${'Pythagoras'}
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></lion-checkbox>
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</lion-checkbox-indeterminate>
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<lion-checkbox-indeterminate label="17th Century scientists">
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<lion-checkbox
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slot="checkbox"
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label="Isaac Newton"
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.choiceValue=${'Isaac Newton'}
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></lion-checkbox>
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<lion-checkbox
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slot="checkbox"
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label="Galileo Galilei"
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.choiceValue=${'Galileo Galilei'}
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></lion-checkbox>
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</lion-checkbox-indeterminate>
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</lion-checkbox-group>
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`;
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```
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The `checkbox-indeterminate` can have another `checkbox-indeterminate` as a child.
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```js preview-story
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export const indeterminateChildren = () => html`
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<lion-checkbox-group name="scientists[]" label="Favorite scientists">
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<lion-checkbox-indeterminate label="Scientists">
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<lion-checkbox
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slot="checkbox"
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label="Isaac Newton"
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.choiceValue=${'Isaac Newton'}
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></lion-checkbox>
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<lion-checkbox
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slot="checkbox"
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label="Galileo Galilei"
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.choiceValue=${'Galileo Galilei'}
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></lion-checkbox>
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<lion-checkbox-indeterminate slot="checkbox" label="Old Greek scientists">
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<lion-checkbox
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slot="checkbox"
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label="Archimedes"
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.choiceValue=${'Archimedes'}
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></lion-checkbox>
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<lion-checkbox slot="checkbox" label="Plato" .choiceValue=${'Plato'}></lion-checkbox>
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<lion-checkbox
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slot="checkbox"
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label="Pythagoras"
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.choiceValue=${'Pythagoras'}
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></lion-checkbox>
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</lion-checkbox-indeterminate>
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</lion-checkbox-indeterminate>
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</lion-checkbox-group>
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`;
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```
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You can also use `mixed-state` attribute so your indeterminate checkbox toggles through three states (indeterminate, checked, unchecked), where for indeterminate state the old children states are restored when you toggle back into this.
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```js preview-story
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export const mixedState = () => html`
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<lion-checkbox-group name="scientists[]" label="Favorite scientists">
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<lion-checkbox-indeterminate mixed-state label="Scientists">
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<lion-checkbox
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slot="checkbox"
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label="Isaac Newton"
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.choiceValue=${'Isaac Newton'}
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></lion-checkbox>
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<lion-checkbox
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slot="checkbox"
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label="Galileo Galilei"
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.choiceValue=${'Galileo Galilei'}
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></lion-checkbox>
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<lion-checkbox-indeterminate mixed-state slot="checkbox" label="Old Greek scientists">
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<lion-checkbox
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slot="checkbox"
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label="Archimedes"
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.choiceValue=${'Archimedes'}
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></lion-checkbox>
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<lion-checkbox slot="checkbox" label="Plato" .choiceValue=${'Plato'}></lion-checkbox>
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<lion-checkbox
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slot="checkbox"
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label="Pythagoras"
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.choiceValue=${'Pythagoras'}
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></lion-checkbox>
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</lion-checkbox-indeterminate>
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</lion-checkbox-indeterminate>
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</lion-checkbox-group>
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`;
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```
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