Rewrite AnimatedNumber component with React hooks (#24559)

app/javascript/mastodon/components/animated_number.jsx

@@ -1,76 +0,0 @@
-import React from 'react';
-import PropTypes from 'prop-types';
-import ShortNumber from 'mastodon/components/short_number';
-import TransitionMotion from 'react-motion/lib/TransitionMotion';
-import spring from 'react-motion/lib/spring';
-import { reduceMotion } from 'mastodon/initial_state';
-
-const obfuscatedCount = count => {
-  if (count < 0) {
-    return 0;
-  } else if (count <= 1) {
-    return count;
-  } else {
-    return '1+';
-  }
-};
-
-export default class AnimatedNumber extends React.PureComponent {
-
-  static propTypes = {
-    value: PropTypes.number.isRequired,
-    obfuscate: PropTypes.bool,
-  };
-
-  state = {
-    direction: 1,
-  };
-
-  componentWillReceiveProps (nextProps) {
-    if (nextProps.value > this.props.value) {
-      this.setState({ direction: 1 });
-    } else if (nextProps.value < this.props.value) {
-      this.setState({ direction: -1 });
-    }
-  }
-
-  willEnter = () => {
-    const { direction } = this.state;
-
-    return { y: -1 * direction };
-  };
-
-  willLeave = () => {
-    const { direction } = this.state;
-
-    return { y: spring(1 * direction, { damping: 35, stiffness: 400 }) };
-  };
-
-  render () {
-    const { value, obfuscate } = this.props;
-    const { direction } = this.state;
-
-    if (reduceMotion) {
-      return obfuscate ? obfuscatedCount(value) : <ShortNumber value={value} />;
-    }
-
-    const styles = [{
-      key: `${value}`,
-      data: value,
-      style: { y: spring(0, { damping: 35, stiffness: 400 }) },
-    }];
-
-    return (
-      <TransitionMotion styles={styles} willEnter={this.willEnter} willLeave={this.willLeave}>
-        {items => (
-          <span className='animated-number'>
-            {items.map(({ key, data, style }) => (
-              <span key={key} style={{ position: (direction * style.y) > 0 ? 'absolute' : 'static', transform: `translateY(${style.y * 100}%)` }}>{obfuscate ? obfuscatedCount(data) : <ShortNumber value={data} />}</span>
-            ))}
-          </span>
-        )}
-      </TransitionMotion>
-    );
-  }
-
-}

app/javascript/mastodon/components/animated_number.tsx

@@ -0,0 +1,58 @@
+import React, { useCallback, useState } from 'react';
+import ShortNumber from './short_number';
+import { TransitionMotion, spring } from 'react-motion';
+import { reduceMotion } from '../initial_state';
+
+const obfuscatedCount = (count: number) => {
+  if (count < 0) {
+    return 0;
+  } else if (count <= 1) {
+    return count;
+  } else {
+    return '1+';
+  }
+};
+
+type Props = {
+  value: number;
+  obfuscate?: boolean;
+}
+export const AnimatedNumber: React.FC<Props> = ({
+  value,
+  obfuscate,
+})=> {
+  const [previousValue, setPreviousValue] = useState(value);
+  const [direction, setDirection] = useState<1|-1>(1);
+
+  if (previousValue !== value) {
+    setPreviousValue(value);
+    setDirection(value > previousValue ? 1 : -1);
+  }
+
+  const willEnter = useCallback(() => ({ y: -1 * direction }), [direction]);
+  const willLeave = useCallback(() => ({ y: spring(1 * direction, { damping: 35, stiffness: 400 }) }), [direction]);
+
+  if (reduceMotion) {
+    return obfuscate ? <>{obfuscatedCount(value)}</> : <ShortNumber value={value} />;
+  }
+
+  const styles = [{
+    key: `${value}`,
+    data: value,
+    style: { y: spring(0, { damping: 35, stiffness: 400 }) },
+  }];
+
+  return (
+    <TransitionMotion styles={styles} willEnter={willEnter} willLeave={willLeave}>
+      {items => (
+        <span className='animated-number'>
+          {items.map(({ key, data, style }) => (
+            <span key={key} style={{ position: (direction * style.y) > 0 ? 'absolute' : 'static', transform: `translateY(${style.y * 100}%)` }}>{obfuscate ? obfuscatedCount(data) : <ShortNumber value={data} />}</span>
+          ))}
+        </span>
+      )}
+    </TransitionMotion>
+  );
+};
+
+export default AnimatedNumber;