puppeteer-core
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A high-level API to control headless Chrome over the DevTools Protocol
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JavaScript
/**
* @license
* Copyright 2018 Google Inc.
* SPDX-License-Identifier: Apache-2.0
*/
var __addDisposableResource = (this && this.__addDisposableResource) || function (env, value, async) {
if (value !== null && value !== void 0) {
if (typeof value !== "object" && typeof value !== "function") throw new TypeError("Object expected.");
var dispose, inner;
if (async) {
if (!Symbol.asyncDispose) throw new TypeError("Symbol.asyncDispose is not defined.");
dispose = value[Symbol.asyncDispose];
}
if (dispose === void 0) {
if (!Symbol.dispose) throw new TypeError("Symbol.dispose is not defined.");
dispose = value[Symbol.dispose];
if (async) inner = dispose;
}
if (typeof dispose !== "function") throw new TypeError("Object not disposable.");
if (inner) dispose = function() { try { inner.call(this); } catch (e) { return Promise.reject(e); } };
env.stack.push({ value: value, dispose: dispose, async: async });
}
else if (async) {
env.stack.push({ async: true });
}
return value;
};
var __disposeResources = (this && this.__disposeResources) || (function (SuppressedError) {
return function (env) {
function fail(e) {
env.error = env.hasError ? new SuppressedError(e, env.error, "An error was suppressed during disposal.") : e;
env.hasError = true;
}
var r, s = 0;
function next() {
while (r = env.stack.pop()) {
try {
if (!r.async && s === 1) return s = 0, env.stack.push(r), Promise.resolve().then(next);
if (r.dispose) {
var result = r.dispose.call(r.value);
if (r.async) return s |= 2, Promise.resolve(result).then(next, function(e) { fail(e); return next(); });
}
else s |= 1;
}
catch (e) {
fail(e);
}
}
if (s === 1) return env.hasError ? Promise.reject(env.error) : Promise.resolve();
if (env.hasError) throw env.error;
}
return next();
};
})(typeof SuppressedError === "function" ? SuppressedError : function (error, suppressed, message) {
var e = new Error(message);
return e.name = "SuppressedError", e.error = error, e.suppressed = suppressed, e;
});
/**
* The Accessibility class provides methods for inspecting the browser's
* accessibility tree. The accessibility tree is used by assistive technology
* such as {@link https://en.wikipedia.org/wiki/Screen_reader | screen readers} or
* {@link https://en.wikipedia.org/wiki/Switch_access | switches}.
*
* @remarks
*
* Accessibility is a very platform-specific thing. On different platforms,
* there are different screen readers that might have wildly different output.
*
* Blink - Chrome's rendering engine - has a concept of "accessibility tree",
* which is then translated into different platform-specific APIs. Accessibility
* namespace gives users access to the Blink Accessibility Tree.
*
* Most of the accessibility tree gets filtered out when converting from Blink
* AX Tree to Platform-specific AX-Tree or by assistive technologies themselves.
* By default, Puppeteer tries to approximate this filtering, exposing only
* the "interesting" nodes of the tree.
*
* @public
*/
export class Accessibility {
#realm;
#frameId;
/**
* @internal
*/
constructor(realm, frameId = '') {
this.#realm = realm;
this.#frameId = frameId;
}
/**
* Captures the current state of the accessibility tree.
* The returned object represents the root accessible node of the page.
*
* @remarks
*
* **NOTE** The Chrome accessibility tree contains nodes that go unused on
* most platforms and by most screen readers. Puppeteer will discard them as
* well for an easier to process tree, unless `interestingOnly` is set to
* `false`.
*
* @example
* An example of dumping the entire accessibility tree:
*
* ```ts
* const snapshot = await page.accessibility.snapshot();
* console.log(snapshot);
* ```
*
* @example
* An example of logging the focused node's name:
*
* ```ts
* const snapshot = await page.accessibility.snapshot();
* const node = findFocusedNode(snapshot);
* console.log(node && node.name);
*
* function findFocusedNode(node) {
* if (node.focused) return node;
* for (const child of node.children || []) {
* const foundNode = findFocusedNode(child);
* return foundNode;
* }
* return null;
* }
* ```
*
* @returns An AXNode object representing the snapshot.
*/
async snapshot(options = {}) {
const { interestingOnly = true, root = null, includeIframes = false, } = options;
const { nodes } = await this.#realm.environment.client.send('Accessibility.getFullAXTree', {
frameId: this.#frameId,
});
let backendNodeId;
if (root) {
const { node } = await this.#realm.environment.client.send('DOM.describeNode', {
objectId: root.id,
});
backendNodeId = node.backendNodeId;
}
const defaultRoot = AXNode.createTree(this.#realm, nodes);
const populateIframes = async (root) => {
if (root.payload.role?.value === 'Iframe') {
const env_1 = { stack: [], error: void 0, hasError: false };
try {
if (!root.payload.backendDOMNodeId) {
return;
}
const handle = __addDisposableResource(env_1, (await this.#realm.adoptBackendNode(root.payload.backendDOMNodeId)), false);
if (!handle || !('contentFrame' in handle)) {
return;
}
const frame = await handle.contentFrame();
if (!frame) {
return;
}
const iframeSnapshot = await frame.accessibility.snapshot(options);
root.iframeSnapshot = iframeSnapshot ?? undefined;
}
catch (e_1) {
env_1.error = e_1;
env_1.hasError = true;
}
finally {
__disposeResources(env_1);
}
}
for (const child of root.children) {
await populateIframes(child);
}
};
let needle = defaultRoot;
if (!defaultRoot) {
return null;
}
if (includeIframes) {
await populateIframes(defaultRoot);
}
if (backendNodeId) {
needle = defaultRoot.find(node => {
return node.payload.backendDOMNodeId === backendNodeId;
});
}
if (!needle) {
return null;
}
if (!interestingOnly) {
return this.serializeTree(needle)[0] ?? null;
}
const interestingNodes = new Set();
this.collectInterestingNodes(interestingNodes, defaultRoot, false);
if (!interestingNodes.has(needle)) {
return null;
}
return this.serializeTree(needle, interestingNodes)[0] ?? null;
}
serializeTree(node, interestingNodes) {
const children = [];
for (const child of node.children) {
children.push(...this.serializeTree(child, interestingNodes));
}
if (interestingNodes && !interestingNodes.has(node)) {
return children;
}
const serializedNode = node.serialize();
if (children.length) {
serializedNode.children = children;
}
if (node.iframeSnapshot) {
if (!serializedNode.children) {
serializedNode.children = [];
}
serializedNode.children.push(node.iframeSnapshot);
}
return [serializedNode];
}
collectInterestingNodes(collection, node, insideControl) {
if (node.isInteresting(insideControl) || node.iframeSnapshot) {
collection.add(node);
}
if (node.isLeafNode()) {
return;
}
insideControl = insideControl || node.isControl();
for (const child of node.children) {
this.collectInterestingNodes(collection, child, insideControl);
}
}
}
class AXNode {
payload;
children = [];
iframeSnapshot;
#richlyEditable = false;
#editable = false;
#focusable = false;
#hidden = false;
#name;
#role;
#ignored;
#cachedHasFocusableChild;
#realm;
constructor(realm, payload) {
this.payload = payload;
this.#name = this.payload.name ? this.payload.name.value : '';
this.#role = this.payload.role ? this.payload.role.value : 'Unknown';
this.#ignored = this.payload.ignored;
this.#realm = realm;
for (const property of this.payload.properties || []) {
if (property.name === 'editable') {
this.#richlyEditable = property.value.value === 'richtext';
this.#editable = true;
}
if (property.name === 'focusable') {
this.#focusable = property.value.value;
}
if (property.name === 'hidden') {
this.#hidden = property.value.value;
}
}
}
#isPlainTextField() {
if (this.#richlyEditable) {
return false;
}
if (this.#editable) {
return true;
}
return this.#role === 'textbox' || this.#role === 'searchbox';
}
#isTextOnlyObject() {
const role = this.#role;
return (role === 'LineBreak' ||
role === 'text' ||
role === 'InlineTextBox' ||
role === 'StaticText');
}
#hasFocusableChild() {
if (this.#cachedHasFocusableChild === undefined) {
this.#cachedHasFocusableChild = false;
for (const child of this.children) {
if (child.#focusable || child.#hasFocusableChild()) {
this.#cachedHasFocusableChild = true;
break;
}
}
}
return this.#cachedHasFocusableChild;
}
find(predicate) {
if (predicate(this)) {
return this;
}
for (const child of this.children) {
const result = child.find(predicate);
if (result) {
return result;
}
}
return null;
}
isLeafNode() {
if (!this.children.length) {
return true;
}
// These types of objects may have children that we use as internal
// implementation details, but we want to expose them as leaves to platform
// accessibility APIs because screen readers might be confused if they find
// any children.
if (this.#isPlainTextField() || this.#isTextOnlyObject()) {
return true;
}
// Roles whose children are only presentational according to the ARIA and
// HTML5 Specs should be hidden from screen readers.
// (Note that whilst ARIA buttons can have only presentational children, HTML5
// buttons are allowed to have content.)
switch (this.#role) {
case 'doc-cover':
case 'graphics-symbol':
case 'img':
case 'image':
case 'Meter':
case 'scrollbar':
case 'slider':
case 'separator':
case 'progressbar':
return true;
default:
break;
}
// Here and below: Android heuristics
if (this.#hasFocusableChild()) {
return false;
}
if (this.#focusable && this.#name) {
return true;
}
if (this.#role === 'heading' && this.#name) {
return true;
}
return false;
}
isControl() {
switch (this.#role) {
case 'button':
case 'checkbox':
case 'ColorWell':
case 'combobox':
case 'DisclosureTriangle':
case 'listbox':
case 'menu':
case 'menubar':
case 'menuitem':
case 'menuitemcheckbox':
case 'menuitemradio':
case 'radio':
case 'scrollbar':
case 'searchbox':
case 'slider':
case 'spinbutton':
case 'switch':
case 'tab':
case 'textbox':
case 'tree':
case 'treeitem':
return true;
default:
return false;
}
}
isInteresting(insideControl) {
const role = this.#role;
if (role === 'Ignored' || this.#hidden || this.#ignored) {
return false;
}
if (this.#focusable || this.#richlyEditable) {
return true;
}
// If it's not focusable but has a control role, then it's interesting.
if (this.isControl()) {
return true;
}
// A non focusable child of a control is not interesting
if (insideControl) {
return false;
}
return this.isLeafNode() && !!this.#name;
}
serialize() {
const properties = new Map();
for (const property of this.payload.properties || []) {
properties.set(property.name.toLowerCase(), property.value.value);
}
if (this.payload.name) {
properties.set('name', this.payload.name.value);
}
if (this.payload.value) {
properties.set('value', this.payload.value.value);
}
if (this.payload.description) {
properties.set('description', this.payload.description.value);
}
const node = {
role: this.#role,
elementHandle: async () => {
if (!this.payload.backendDOMNodeId) {
return null;
}
return (await this.#realm.adoptBackendNode(this.payload.backendDOMNodeId));
},
};
const userStringProperties = [
'name',
'value',
'description',
'keyshortcuts',
'roledescription',
'valuetext',
];
const getUserStringPropertyValue = (key) => {
return properties.get(key);
};
for (const userStringProperty of userStringProperties) {
if (!properties.has(userStringProperty)) {
continue;
}
node[userStringProperty] = getUserStringPropertyValue(userStringProperty);
}
const booleanProperties = [
'disabled',
'expanded',
'focused',
'modal',
'multiline',
'multiselectable',
'readonly',
'required',
'selected',
];
const getBooleanPropertyValue = (key) => {
return properties.get(key);
};
for (const booleanProperty of booleanProperties) {
// RootWebArea's treat focus differently than other nodes. They report whether
// their frame has focus, not whether focus is specifically on the root
// node.
if (booleanProperty === 'focused' && this.#role === 'RootWebArea') {
continue;
}
const value = getBooleanPropertyValue(booleanProperty);
if (!value) {
continue;
}
node[booleanProperty] = getBooleanPropertyValue(booleanProperty);
}
const tristateProperties = ['checked', 'pressed'];
for (const tristateProperty of tristateProperties) {
if (!properties.has(tristateProperty)) {
continue;
}
const value = properties.get(tristateProperty);
node[tristateProperty] =
value === 'mixed' ? 'mixed' : value === 'true' ? true : false;
}
const numericalProperties = [
'level',
'valuemax',
'valuemin',
];
const getNumericalPropertyValue = (key) => {
return properties.get(key);
};
for (const numericalProperty of numericalProperties) {
if (!properties.has(numericalProperty)) {
continue;
}
node[numericalProperty] = getNumericalPropertyValue(numericalProperty);
}
const tokenProperties = [
'autocomplete',
'haspopup',
'invalid',
'orientation',
];
const getTokenPropertyValue = (key) => {
return properties.get(key);
};
for (const tokenProperty of tokenProperties) {
const value = getTokenPropertyValue(tokenProperty);
if (!value || value === 'false') {
continue;
}
node[tokenProperty] = getTokenPropertyValue(tokenProperty);
}
return node;
}
static createTree(realm, payloads) {
const nodeById = new Map();
for (const payload of payloads) {
nodeById.set(payload.nodeId, new AXNode(realm, payload));
}
for (const node of nodeById.values()) {
for (const childId of node.payload.childIds || []) {
const child = nodeById.get(childId);
if (child) {
node.children.push(child);
}
}
}
return nodeById.values().next().value ?? null;
}
}
//# sourceMappingURL=Accessibility.js.map