[New] add getAccessibleChildText util

Author: mattxwang

__tests__/src/util/getAccessibleChildText-test.js

@@ -0,0 +1,96 @@
+import expect from 'expect';
+import { elementType } from 'jsx-ast-utils';
+import getAccessibleChildText from '../../../src/util/getAccessibleChildText';
+import JSXAttributeMock from '../../../__mocks__/JSXAttributeMock';
+import JSXElementMock from '../../../__mocks__/JSXElementMock';
+
+describe('getAccessibleChildText', () => {
+  it('returns the aria-label when present', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [JSXAttributeMock('aria-label', 'foo')],
+    ), elementType)).toBe('foo');
+  });
+
+  it('returns the aria-label instead of children', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [JSXAttributeMock('aria-label', 'foo')],
+      [{ type: 'JSXText', value: 'bar' }],
+    ), elementType)).toBe('foo');
+  });
+
+  it('skips elements with aria-hidden=true', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [JSXAttributeMock('aria-hidden', 'true')],
+    ), elementType)).toBe('');
+  });
+
+  it('returns literal value for JSXText child', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [],
+      [{ type: 'JSXText', value: 'bar' }],
+    ), elementType)).toBe('bar');
+  });
+
+  it('returns literal value for JSXText child', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [],
+      [{ type: 'Literal', value: 'bar' }],
+    ), elementType)).toBe('bar');
+  });
+
+  it('returns recursive value for JSXElement child', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [],
+      [JSXElementMock(
+        'span',
+        [],
+        [{ type: 'Literal', value: 'bar' }],
+      )],
+    ), elementType)).toBe('bar');
+  });
+
+  it('skips children with aria-hidden-true', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [],
+      [JSXElementMock(
+        'span',
+        [],
+        [JSXElementMock(
+          'span',
+          [JSXAttributeMock('aria-hidden', 'true')],
+        )],
+      )],
+    ), elementType)).toBe('');
+  });
+
+  it('joins multiple children properly - no spacing', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [],
+      [{ type: 'Literal', value: 'foo' }, { type: 'Literal', value: 'bar' }],
+    ), elementType)).toBe('foo bar');
+  });
+
+  it('joins multiple children properly - with spacing', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [],
+      [{ type: 'Literal', value: ' foo ' }, { type: 'Literal', value: ' bar ' }],
+    ), elementType)).toBe('foo bar');
+  });
+
+  it('skips unknown elements', () => {
+    expect(getAccessibleChildText(JSXElementMock(
+      'a',
+      [],
+      [{ type: 'Literal', value: 'foo' }, { type: 'Unknown' }, { type: 'Literal', value: 'bar' }],
+    ), elementType)).toBe('foo bar');
+  });
+});

src/util/getAccessibleChildText.js

@@ -0,0 +1,55 @@
+// @flow
+
+import type { JSXElement, JSXOpeningElement, Node } from 'ast-types-flow';
+
+import { getProp, getLiteralPropValue } from 'jsx-ast-utils';
+
+import isHiddenFromScreenReader from './isHiddenFromScreenReader';
+
+/**
+ * Returns a new "standardized" string: all whitespace is collapsed to one space,
+ * and the string is lowercase
+ * @param {string} input
+ * @returns lowercase, single-spaced, trimmed string
+ */
+function standardizeSpaceAndCase(input: string): string {
+  return input.trim().replace(/\s\s+/g, ' ').toLowerCase();
+}
+
+/**
+ * Returns the (recursively-defined) accessible child text of a node, which (in-order) is:
+ * 1. The element's aria-label
+ * 2. If the element is a direct literal, the literal value
+ * 3. Otherwise, merge all of its children
+ * @param {JSXElement} node - node to traverse
+ * @returns child text as a string
+ */
+export default function getAccessibleChildText(node: JSXElement, elementType: (JSXOpeningElement) => string): string {
+  const ariaLabel = getLiteralPropValue(getProp(node.openingElement.attributes, 'aria-label'));
+  // early escape-hatch when aria-label is applied
+  if (ariaLabel) return standardizeSpaceAndCase(ariaLabel);
+
+  // skip if aria-hidden is true
+  if (
+    isHiddenFromScreenReader(
+      elementType(node.openingElement),
+      node.openingElement.attributes,
+    )
+  ) {
+    return '';
+  }
+
+  const rawChildText = node.children
+    .map((currentNode: Node): string => {
+      // $FlowFixMe JSXText is missing in ast-types-flow
+      if (currentNode.type === 'Literal' || currentNode.type === 'JSXText') {
+        return String(currentNode.value);
+      }
+      if (currentNode.type === 'JSXElement') {
+        return getAccessibleChildText(currentNode, elementType);
+      }
+      return '';
+    }).join(' ');
+
+  return standardizeSpaceAndCase(rawChildText);
+}