Add character count

UNRELEASED.md

@@ -10,6 +10,8 @@ Use [the changelog guidelines](https://git.io/polaris-changelog-guidelines) to f
 
 ### Enhancements
 
+- `TextField` accepts a `showCharacterCount` prop to enable the display of character count ([#709](https://github.com/Shopify/polaris-react/pull/709))
+
 ### Bug fixes
 
 - Fixed vertical misalignment in `Banner.Header`([#870](https://github.com/Shopify/polaris-react/pull/870))

src/components/TextField/README.md

@@ -497,7 +497,7 @@ class HelpTextExample extends React.Component {
 
 Use as a special form of help text that works best inline.
 
-- Use a prefix for things like currency symbols (e.g. “$”, “¥”, “£”).
+- Use a prefix for things like currency symbols (e.g. “\$”, “¥”, “£”).
 - Use suffix for things like units of measure (e.g. “in”, “cm”).
 
 ```jsx
@@ -737,6 +737,36 @@ Use to show that a textfield is not available for interaction. Most often used i
 <TextField label="Store name" disabled />
 ```
 
+### Text field with character count
+
+<!-- example-for: web -->
+
+Use to display the current number of characters in a text field. Use in conjunction with max length to display the current remaining number of characters in the text field.
+
+```jsx
+class TextFieldExample extends React.Component {
+  state = {
+    value: 'Jaded Pixel',
+  };
+
+  handleChange = (value) => {
+    this.setState({value});
+  };
+
+  render() {
+    return (
+      <TextField
+        label="Store name"
+        value={this.state.value}
+        onChange={this.handleChange}
+        maxLength={20}
+        showCharacterCount
+      />
+    );
+  }
+}
+```
+
 ---
 
 ## Related components

src/components/TextField/TextField.scss

@@ -170,6 +170,18 @@ $stacking-order: (
   pointer-events: none;
 }
 
+.CharacterCount {
+  @include text-emphasis-subdued;
+  z-index: z-index(contents, $stacking-order);
+  margin-right: $backdrop-horizontal-spacing;
+  line-height: control-height();
+  pointer-events: none;
+}
+
+.AlignFieldBottom {
+  align-self: flex-end;
+}
+
 .Spinner {
   z-index: z-index(contents, $stacking-order);
   display: flex;

src/components/TextField/TextField.tsx

@@ -7,6 +7,7 @@ import Labelled, {Action, helpTextID, labelID} from '../Labelled';
 import Connected from '../Connected';
 
 import {Error, Key} from '../../types';
+import {withAppProvider, WithAppProviderProps} from '../AppProvider';
 import {Resizer, Spinner} from './components';
 import * as styles from './TextField.scss';
 
@@ -96,6 +97,8 @@ export interface BaseProps {
   ariaActiveDescendant?: string;
   /** Indicates what kind of user input completion suggestions are provided */
   ariaAutocomplete?: string;
+  /** Indicates whether or not the character count should be displayed */
+  showCharacterCount?: boolean;
   /** Callback when value is changed */
   onChange?(value: string, id: string): void;
   /** Callback when input is focused */
@@ -112,17 +115,19 @@ export type Props = NonMutuallyExclusiveProps &
     | {disabled: true}
     | {onChange(value: string, id: string): void});
 
+export type CombinedProps = Props & WithAppProviderProps;
+
 const getUniqueID = createUniqueIDFactory('TextField');
 
-export default class TextField extends React.PureComponent<Props, State> {
-  static getDerivedStateFromProps(nextProps: Props, prevState: State) {
+class TextField extends React.PureComponent<CombinedProps, State> {
+  static getDerivedStateFromProps(nextProps: CombinedProps, prevState: State) {
     return {id: nextProps.id || prevState.id};
   }
 
   private input: HTMLElement;
   private buttonPressTimer: number;
 
-  constructor(props: Props) {
+  constructor(props: CombinedProps) {
     super(props);
 
     this.state = {
@@ -132,7 +137,7 @@ export default class TextField extends React.PureComponent<Props, State> {
     };
   }
 
-  componentDidUpdate({focused}: Props) {
+  componentDidUpdate({focused}: CombinedProps) {
     if (
       this.input &&
       focused !== this.props.focused &&
@@ -177,6 +182,8 @@ export default class TextField extends React.PureComponent<Props, State> {
       ariaActiveDescendant,
       ariaAutocomplete,
       ariaControls,
+      showCharacterCount,
+      polaris: {intl},
     } = this.props;
 
     const {height} = this.state;
@@ -205,6 +212,35 @@ export default class TextField extends React.PureComponent<Props, State> {
       </div>
     ) : null;
 
+    const characterCount = value.length;
+    const characterCountLabel = intl.translate(
+      maxLength
+        ? 'Polaris.TextField.characterCountWithMaxLength'
+        : 'Polaris.TextField.characterCount',
+      {count: characterCount, limit: maxLength},
+    );
+
+    const characterCountClassName = classNames(
+      styles.CharacterCount,
+      multiline && styles.AlignFieldBottom,
+    );
+
+    const characterCountText = !maxLength
+      ? characterCount
+      : `${characterCount}/${maxLength}`;
+
+    const characterCountMarkup = showCharacterCount ? (
+      <div
+        id={`${id}CharacterCounter`}
+        className={characterCountClassName}
+        aria-label={characterCountLabel}
+        aria-live="polite"
+        aria-atomic="true"
+      >
+        {characterCountText}
+      </div>
+    ) : null;
+
     const spinnerMarkup =
       type === 'number' && !disabled ? (
         <Spinner
@@ -232,6 +268,9 @@ export default class TextField extends React.PureComponent<Props, State> {
     if (helpText) {
       describedBy.push(helpTextID(id));
     }
+    if (showCharacterCount) {
+      describedBy.push(`${id}CharacterCounter`);
+    }
 
     const labelledBy = [labelID(id)];
     if (prefix) {
@@ -303,6 +342,7 @@ export default class TextField extends React.PureComponent<Props, State> {
             {prefixMarkup}
             {input}
             {suffixMarkup}
+            {characterCountMarkup}
             {spinnerMarkup}
             <div className={styles.Backdrop} />
             {resizer}
@@ -414,3 +454,5 @@ function normalizeAutoComplete(autoComplete?: boolean) {
   }
   return autoComplete ? 'on' : 'off';
 }
+
+export default withAppProvider<Props>()(TextField);

src/components/TextField/tests/TextField.test.tsx

@@ -305,6 +305,41 @@ describe('<TextField />', () => {
     });
   });
 
+  describe('characterCount', () => {
+    it('displays number of characters entered in input field', () => {
+      const textField = mountWithAppProvider(
+        <TextField
+          value="test"
+          showCharacterCount
+          label="TextField"
+          id="MyField"
+          onChange={noop}
+        />,
+      );
+
+      const characterCount = textField.find('#MyFieldCharacterCounter');
+
+      expect(characterCount.text()).toBe('4');
+    });
+
+    it('displays remaining characters as fraction in input field with maxLength', () => {
+      const textField = mountWithAppProvider(
+        <TextField
+          value="test"
+          maxLength={10}
+          showCharacterCount
+          label="TextField"
+          id="MyField"
+          onChange={noop}
+        />,
+      );
+
+      const characterCount = textField.find('#MyFieldCharacterCounter');
+
+      expect(characterCount.text()).toBe('4/10');
+    });
+  });
+
   describe('type', () => {
     it('sets the type on the input', () => {
       const type = shallowWithAppProvider(

src/locales/en.json

@@ -192,6 +192,11 @@
 
     "Tag": {
       "ariaLabel": "Remove {children}"
+    },
+
+    "TextField": {
+      "characterCount": "{count} characters",
+      "characterCountWithMaxLength": "{count} of {limit} characters used"
     }
   }
 }