/**
* @license
* Copyright 2023 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
/**
* Activates the first non-disabled item of a given array of items.
*
* @param items {Array<ListItem>} The items from which to activate the
* first item.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
*/
export function activateFirstItem(items, isActivatable = (isItemNotDisabled)) {
// NOTE: These selector functions are static and not on the instance such
// that multiple operations can be chained and we do not have to re-query
// the DOM
const firstItem = getFirstActivatableItem(items, isActivatable);
if (firstItem) {
firstItem.tabIndex = 0;
firstItem.focus();
}
return firstItem;
}
/**
* Activates the last non-disabled item of a given array of items.
*
* @param items {Array<ListItem>} The items from which to activate the
* last item.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
* @nocollapse
*/
export function activateLastItem(items, isActivatable = (isItemNotDisabled)) {
const lastItem = getLastActivatableItem(items, isActivatable);
if (lastItem) {
lastItem.tabIndex = 0;
lastItem.focus();
}
return lastItem;
}
/**
* Deactivates the currently active item of a given array of items.
*
* @param items {Array<ListItem>} The items from which to deactivate the
* active item.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
* @return A record of the deleselcted activated item including the item and
* the index of the item or `null` if none are deactivated.
* @nocollapse
*/
export function deactivateActiveItem(items, isActivatable = (isItemNotDisabled)) {
const activeItem = getActiveItem(items, isActivatable);
if (activeItem) {
activeItem.item.tabIndex = -1;
}
return activeItem;
}
/**
* Retrieves the first activated item of a given array of items.
*
* @param items {Array<ListItem>} The items to search.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
* @return A record of the first activated item including the item and the
* index of the item or `null` if none are activated.
* @nocollapse
*/
export function getActiveItem(items, isActivatable = (isItemNotDisabled)) {
for (let i = 0; i < items.length; i++) {
const item = items[i];
if (item.tabIndex === 0 && isActivatable(item)) {
return {
item,
index: i,
};
}
}
return null;
}
/**
* Retrieves the first non-disabled item of a given array of items. This
* the first item that is not disabled.
*
* @param items {Array<ListItem>} The items to search.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
* @return The first activatable item or `null` if none are activatable.
* @nocollapse
*/
export function getFirstActivatableItem(items, isActivatable = (isItemNotDisabled)) {
for (const item of items) {
if (isActivatable(item)) {
return item;
}
}
return null;
}
/**
* Retrieves the last non-disabled item of a given array of items.
*
* @param items {Array<ListItem>} The items to search.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
* @return The last activatable item or `null` if none are activatable.
* @nocollapse
*/
export function getLastActivatableItem(items, isActivatable = (isItemNotDisabled)) {
for (let i = items.length - 1; i >= 0; i--) {
const item = items[i];
if (isActivatable(item)) {
return item;
}
}
return null;
}
/**
* Retrieves the next non-disabled item of a given array of items.
*
* @param items {Array<ListItem>} The items to search.
* @param index {{index: number}} The index to search from.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
* @param wrap If true, then the next item at the end of the list is the first
* item. Defaults to true.
* @return The next activatable item or `null` if none are activatable.
*/
export function getNextItem(items, index, isActivatable = (isItemNotDisabled), wrap = true) {
for (let i = 1; i < items.length; i++) {
const nextIndex = (i + index) % items.length;
if (nextIndex < index && !wrap) {
// Return if the index loops back to the beginning and not wrapping.
return null;
}
const item = items[nextIndex];
if (isActivatable(item)) {
return item;
}
}
return items[index] ? items[index] : null;
}
/**
* Retrieves the previous non-disabled item of a given array of items.
*
* @param items {Array<ListItem>} The items to search.
* @param index {{index: number}} The index to search from.
* @param isActivatable Function to determine if an item can be activated.
* Defaults to non-disabled items.
* @param wrap If true, then the previous item at the beginning of the list is
* the last item. Defaults to true.
* @return The previous activatable item or `null` if none are activatable.
*/
export function getPrevItem(items, index, isActivatable = (isItemNotDisabled), wrap = true) {
for (let i = 1; i < items.length; i++) {
const prevIndex = (index - i + items.length) % items.length;
if (prevIndex > index && !wrap) {
// Return if the index loops back to the end and not wrapping.
return null;
}
const item = items[prevIndex];
if (isActivatable(item)) {
return item;
}
}
return items[index] ? items[index] : null;
}
/**
* Activates the next item and focuses it. If nothing is currently activated,
* activates the first item.
*/
export function activateNextItem(items, activeItemRecord, isActivatable = (isItemNotDisabled), wrap = true) {
if (activeItemRecord) {
const next = getNextItem(items, activeItemRecord.index, isActivatable, wrap);
if (next) {
next.tabIndex = 0;
next.focus();
}
return next;
}
else {
return activateFirstItem(items, isActivatable);
}
}
/**
* Activates the previous item and focuses it. If nothing is currently
* activated, activates the last item.
*/
export function activatePreviousItem(items, activeItemRecord, isActivatable = (isItemNotDisabled), wrap = true) {
if (activeItemRecord) {
const prev = getPrevItem(items, activeItemRecord.index, isActivatable, wrap);
if (prev) {
prev.tabIndex = 0;
prev.focus();
}
return prev;
}
else {
return activateLastItem(items, isActivatable);
}
}
/**
* Creates an event that requests the parent md-list to deactivate all other
* items.
*/
export function createDeactivateItemsEvent() {
return new Event('deactivate-items', { bubbles: true, composed: true });
}
/**
* Creates an event that requests the menu to set `tabindex=0` on the item and
* focus it. We use this pattern because List keeps track of what element is
* active in the List by maintaining tabindex. We do not want list items
* to set tabindex on themselves or focus themselves so that we can organize all
* that logic in the parent List and Menus, and list item stays as dumb as
* possible.
*/
export function createRequestActivationEvent() {
return new Event('request-activation', { bubbles: true, composed: true });
}
/**
* The default `isActivatable` function, which checks if an item is not
* disabled.
*
* @param item The item to check.
* @return true if `item.disabled` is `false.
*/
function isItemNotDisabled(item) {
return !item.disabled;
}
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