botframework-webchat-component/src/hooks/internal/useChanged.ts

React component of botframework-webchat

import { useRef } from 'react';

/**
 * Returns `true` if the `value` has changed, otherwise, `false`.
 *
 * Note: on initial call, this will return `true`.
 *
 * @param {T} value - The `value` to detect for changes.
 */
export default function useChanged<T>(value: T): boolean {
  const prevValueRef = useRef(value);
  const changed = value !== prevValueRef.current;

  prevValueRef.current = value;

  return changed;
}