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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
"use strict";
loader.lazyRequireGetter(
this,
"CssLogic",
true
);
loader.lazyRequireGetter(
this,
"getCSSStyleRules",
true
);
loader.lazyRequireGetter(
this,
"nodeConstants",
);
loader.lazyRequireGetter(
this,
["isDefunct", "getAriaRoles"],
true
);
const {
accessibility: {
AUDIT_TYPE: { KEYBOARD },
ISSUE_TYPE: {
[KEYBOARD]: {
FOCUSABLE_NO_SEMANTICS,
FOCUSABLE_POSITIVE_TABINDEX,
INTERACTIVE_NO_ACTION,
INTERACTIVE_NOT_FOCUSABLE,
MOUSE_INTERACTIVE_ONLY,
NO_FOCUS_VISIBLE,
},
},
SCORES: { FAIL, WARNING },
},
// Specified by the author CSS rule type.
const STYLE_RULE = 1;
// Accessible action for showing long description.
const CLICK_ACTION = "click";
/**
* Focus specific pseudo classes that the keyboard audit simulates to determine
* focus styling.
*/
const FOCUS_PSEUDO_CLASS = ":focus";
const MOZ_FOCUSRING_PSEUDO_CLASS = ":-moz-focusring";
const KEYBOARD_FOCUSABLE_ROLES = new Set([
Ci.nsIAccessibleRole.ROLE_BUTTONMENU,
Ci.nsIAccessibleRole.ROLE_CHECKBUTTON,
Ci.nsIAccessibleRole.ROLE_COMBOBOX,
Ci.nsIAccessibleRole.ROLE_EDITCOMBOBOX,
Ci.nsIAccessibleRole.ROLE_ENTRY,
Ci.nsIAccessibleRole.ROLE_LINK,
Ci.nsIAccessibleRole.ROLE_LISTBOX,
Ci.nsIAccessibleRole.ROLE_PASSWORD_TEXT,
Ci.nsIAccessibleRole.ROLE_PUSHBUTTON,
Ci.nsIAccessibleRole.ROLE_RADIOBUTTON,
Ci.nsIAccessibleRole.ROLE_SLIDER,
Ci.nsIAccessibleRole.ROLE_SPINBUTTON,
Ci.nsIAccessibleRole.ROLE_SUMMARY,
Ci.nsIAccessibleRole.ROLE_SWITCH,
Ci.nsIAccessibleRole.ROLE_TOGGLE_BUTTON,
]);
const INTERACTIVE_ROLES = new Set([
...KEYBOARD_FOCUSABLE_ROLES,
Ci.nsIAccessibleRole.ROLE_CHECK_MENU_ITEM,
Ci.nsIAccessibleRole.ROLE_CHECK_RICH_OPTION,
Ci.nsIAccessibleRole.ROLE_COMBOBOX_OPTION,
Ci.nsIAccessibleRole.ROLE_MENUITEM,
Ci.nsIAccessibleRole.ROLE_OPTION,
Ci.nsIAccessibleRole.ROLE_OUTLINE,
Ci.nsIAccessibleRole.ROLE_OUTLINEITEM,
Ci.nsIAccessibleRole.ROLE_PAGETAB,
Ci.nsIAccessibleRole.ROLE_PARENT_MENUITEM,
Ci.nsIAccessibleRole.ROLE_RADIO_MENU_ITEM,
Ci.nsIAccessibleRole.ROLE_RICH_OPTION,
]);
const INTERACTIVE_IF_FOCUSABLE_ROLES = new Set([
// If article is focusable, we can assume it is inside a feed.
Ci.nsIAccessibleRole.ROLE_ARTICLE,
// Column header can be focusable.
Ci.nsIAccessibleRole.ROLE_COLUMNHEADER,
Ci.nsIAccessibleRole.ROLE_GRID_CELL,
Ci.nsIAccessibleRole.ROLE_MENUBAR,
Ci.nsIAccessibleRole.ROLE_MENUPOPUP,
Ci.nsIAccessibleRole.ROLE_PAGETABLIST,
// Row header can be focusable.
Ci.nsIAccessibleRole.ROLE_ROWHEADER,
Ci.nsIAccessibleRole.ROLE_SCROLLBAR,
Ci.nsIAccessibleRole.ROLE_SEPARATOR,
Ci.nsIAccessibleRole.ROLE_TOOLBAR,
]);
/**
* Determine if a node is dead or is not an element node.
*
* @param {DOMNode} node
* Node to be tested for validity.
*
* @returns {Boolean}
* True if the node is either dead or is not an element node.
*/
function isInvalidNode(node) {
return (
!node ||
Cu.isDeadWrapper(node) ||
node.nodeType !== nodeConstants.ELEMENT_NODE ||
!node.ownerGlobal
);
}
/**
* Determine if accessible is focusable with the keyboard.
*
* @param {nsIAccessible} accessible
* Accessible for which to determine if it is keyboard focusable.
*
* @returns {Boolean}
* True if focusable with the keyboard.
*/
function isKeyboardFocusable(accessible) {
const state = {};
accessible.getState(state, {});
// State will be focusable even if the tabindex is negative.
return (
state.value & Ci.nsIAccessibleStates.STATE_FOCUSABLE &&
// Platform accessibility will still report STATE_FOCUSABLE even with the
// tabindex="-1" so we need to check that it is >= 0 to be considered
// keyboard focusable.
accessible.DOMNode.tabIndex > -1
);
}
/**
* Determine if a current node has focus specific styling by applying a
* focus-related pseudo class (such as :focus or :-moz-focusring) to a focusable
* node.
*
* @param {DOMNode} focusableNode
* Node to apply focus-related pseudo class to.
* @param {DOMNode} currentNode
* Node to be checked for having focus specific styling.
* @param {String} pseudoClass
* A focus related pseudo-class to be simulated for style comparison.
*
* @returns {Boolean}
* True if the currentNode has focus specific styling.
*/
function hasStylesForFocusRelatedPseudoClass(
focusableNode,
currentNode,
pseudoClass
) {
const defaultRules = getCSSStyleRules(currentNode);
InspectorUtils.addPseudoClassLock(focusableNode, pseudoClass);
// Determine a set of properties that are specific to CSS rules that are only
// present when a focus related pseudo-class is locked in.
const tempRules = getCSSStyleRules(currentNode);
const properties = new Set();
for (const rule of tempRules) {
if (rule.type !== STYLE_RULE) {
continue;
}
if (!defaultRules.includes(rule)) {
for (let index = 0; index < rule.style.length; index++) {
properties.add(rule.style.item(index));
}
}
}
// If there are no focus specific CSS rules or properties, currentNode does
// node have any focus specific styling, we are done.
if (properties.size === 0) {
InspectorUtils.removePseudoClassLock(focusableNode, pseudoClass);
return false;
}
// Determine values for properties that are focus specific.
const tempStyle = CssLogic.getComputedStyle(currentNode);
const focusStyle = {};
for (const name of properties.values()) {
focusStyle[name] = tempStyle.getPropertyValue(name);
}
InspectorUtils.removePseudoClassLock(focusableNode, pseudoClass);
// If values for focus specific properties are different from default style
// values, assume we have focus spefic styles for the currentNode.
const defaultStyle = CssLogic.getComputedStyle(currentNode);
for (const name of properties.values()) {
if (defaultStyle.getPropertyValue(name) !== focusStyle[name]) {
return true;
}
}
return false;
}
/**
* Check if an element node (currentNode) has distinct focus styling. This
* function also takes into account a case when focus styling is applied to a
* descendant too.
*
* @param {DOMNode} focusableNode
* Node to apply focus-related pseudo class to.
* @param {DOMNode} currentNode
* Node to be checked for having focus specific styling.
*
* @returns {Boolean}
* True if the node or its descendant has distinct focus styling.
*/
function hasFocusStyling(focusableNode, currentNode) {
if (isInvalidNode(currentNode)) {
return false;
}
// Check if an element node has distinct :-moz-focusring styling.
const hasStylesForMozFocusring = hasStylesForFocusRelatedPseudoClass(
focusableNode,
currentNode,
MOZ_FOCUSRING_PSEUDO_CLASS
);
if (hasStylesForMozFocusring) {
return true;
}
// Check if an element node has distinct :focus styling.
const hasStylesForFocus = hasStylesForFocusRelatedPseudoClass(
focusableNode,
currentNode,
FOCUS_PSEUDO_CLASS
);
if (hasStylesForFocus) {
return true;
}
// If no element specific focus styles where found, check if its element
// children have them.
for (
let child = currentNode.firstElementChild;
child;
child = currentNode.nextnextElementSibling
) {
if (hasFocusStyling(focusableNode, child)) {
return true;
}
}
return false;
}
/**
* A rule that determines if a focusable accessible object has appropriate focus
* styling.
*
* @param {nsIAccessible} accessible
* Accessible to be checked for being focusable and having focus
* styling.
*
* @return {null|Object}
* Null if accessible has keyboard focus styling, audit report object
* otherwise.
*/
function focusStyleRule(accessible) {
const { DOMNode } = accessible;
if (isInvalidNode(DOMNode)) {
return null;
}
// Ignore non-focusable elements.
if (!isKeyboardFocusable(accessible)) {
return null;
}
if (hasFocusStyling(DOMNode, DOMNode)) {
return null;
}
// If no browser or author focus styling was found, check if the node is a
// widget that is themed by platform native theme.
if (InspectorUtils.isElementThemed(DOMNode)) {
return null;
}
return { score: WARNING, issue: NO_FOCUS_VISIBLE };
}
/**
* A rule that determines if an interactive accessible has any associated
* accessible actions with it. If the element is interactive but and has no
* actions, assistive technology users will not be able to interact with it.
*
* @param {nsIAccessible} accessible
* Accessible to be checked for being interactive and having accessible
* actions.
*
* @return {null|Object}
* Null if accessible is not interactive or if it is and it has
* accessible action associated with it, audit report object otherwise.
*/
function interactiveRule(accessible) {
if (!INTERACTIVE_ROLES.has(accessible.role)) {
return null;
}
if (accessible.actionCount > 0) {
return null;
}
return { score: FAIL, issue: INTERACTIVE_NO_ACTION };
}
/**
* A rule that determines if an interactive accessible is also focusable when
* not disabled.
*
* @param {nsIAccessible} accessible
* Accessible to be checked for being interactive and being focusable
* when enabled.
*
* @return {null|Object}
* Null if accessible is not interactive or if it is and it is focusable
* when enabled, audit report object otherwise.
*/
function focusableRule(accessible) {
if (!KEYBOARD_FOCUSABLE_ROLES.has(accessible.role)) {
return null;
}
const state = {};
accessible.getState(state, {});
// We only expect in interactive accessible object to be focusable if it is
// not disabled.
if (state.value & Ci.nsIAccessibleStates.STATE_UNAVAILABLE) {
return null;
}
if (isKeyboardFocusable(accessible)) {
return null;
}
const ariaRoles = getAriaRoles(accessible);
if (
ariaRoles &&
(ariaRoles.includes("combobox") || ariaRoles.includes("listbox"))
) {
// Do not force ARIA combobox or listbox to be focusable.
return null;
}
return { score: FAIL, issue: INTERACTIVE_NOT_FOCUSABLE };
}
/**
* A rule that determines if a focusable accessible has an associated
* interactive role.
*
* @param {nsIAccessible} accessible
* Accessible to be checked for having an interactive role if it is
* focusable.
*
* @return {null|Object}
* Null if accessible is not interactive or if it is and it has an
* interactive role, audit report object otherwise.
*/
function semanticsRule(accessible) {
if (
INTERACTIVE_ROLES.has(accessible.role) ||
// Visible listboxes will have focusable state when inside comboboxes.
accessible.role === Ci.nsIAccessibleRole.ROLE_COMBOBOX_LIST
) {
return null;
}
if (isKeyboardFocusable(accessible)) {
if (INTERACTIVE_IF_FOCUSABLE_ROLES.has(accessible.role)) {
return null;
}
// ROLE_TABLE is used for grids too which are considered interactive.
if (accessible.role === Ci.nsIAccessibleRole.ROLE_TABLE) {
const ariaRoles = getAriaRoles(accessible);
if (ariaRoles && ariaRoles.includes("grid")) {
return null;
}
}
return { score: WARNING, issue: FOCUSABLE_NO_SEMANTICS };
}
const state = {};
accessible.getState(state, {});
if (
// Ignore text leafs.
accessible.role === Ci.nsIAccessibleRole.ROLE_TEXT_LEAF ||
// Ignore accessibles with no accessible actions.
accessible.actionCount === 0 ||
// Ignore labels that have a label for relation with their target because
// they are clickable.
(accessible.role === Ci.nsIAccessibleRole.ROLE_LABEL &&
accessible.getRelationByType(Ci.nsIAccessibleRelation.RELATION_LABEL_FOR)
.targetsCount > 0) ||
// Ignore images that are inside an anchor (have linked state).
(accessible.role === Ci.nsIAccessibleRole.ROLE_GRAPHIC &&
state.value & Ci.nsIAccessibleStates.STATE_LINKED)
) {
return null;
}
// Ignore anything but a click action in the list of actions.
for (let i = 0; i < accessible.actionCount; i++) {
if (accessible.getActionName(i) === CLICK_ACTION) {
return { score: FAIL, issue: MOUSE_INTERACTIVE_ONLY };
}
}
return null;
}
/**
* A rule that determines if an element associated with a focusable accessible
* has a positive tabindex.
*
* @param {nsIAccessible} accessible
* Accessible to be checked for having an element with positive tabindex
* attribute.
*
* @return {null|Object}
* Null if accessible is not focusable or if it is and its element's
* tabindex attribute is less than 1, audit report object otherwise.
*/
function tabIndexRule(accessible) {
const { DOMNode } = accessible;
if (isInvalidNode(DOMNode)) {
return null;
}
if (!isKeyboardFocusable(accessible)) {
return null;
}
if (DOMNode.tabIndex > 0) {
return { score: WARNING, issue: FOCUSABLE_POSITIVE_TABINDEX };
}
return null;
}
function auditKeyboard(accessible) {
if (isDefunct(accessible)) {
return null;
}
// Do not test anything on accessible objects for documents or frames.
if (
accessible.role === Ci.nsIAccessibleRole.ROLE_DOCUMENT ||
accessible.role === Ci.nsIAccessibleRole.ROLE_INTERNAL_FRAME
) {
return null;
}
// Check if interactive accessible can be used by the assistive
// technology.
let issue = interactiveRule(accessible);
if (issue) {
return issue;
}
// Check if interactive accessible is also focusable when enabled.
issue = focusableRule(accessible);
if (issue) {
return issue;
}
// Check if accessible object has an element with a positive tabindex.
issue = tabIndexRule(accessible);
if (issue) {
return issue;
}
// Check if a focusable accessible has interactive semantics.
issue = semanticsRule(accessible);
if (issue) {
return issue;
}
// Check if focusable accessible has associated focus styling.
issue = focusStyleRule(accessible);
if (issue) {
return issue;
}
return issue;
}
module.exports.auditKeyboard = auditKeyboard;