@mui/base/utils/useTextNavigation.js

import * as React from 'react';
const TEXT_NAVIGATION_RESET_TIMEOUT = 500; // milliseconds

/**
 * @ignore - internal hook.
 *
 * Provides a handler for text navigation.
 * It's used to navigate a list by typing the first letters of the options.
 *
 * @param callback A function to be called when the navigation should be performed.
 * @returns A function to be used in a keydown event handler.
 */
export default function useTextNavigation(callback) {
  const textCriteriaRef = React.useRef({
    searchString: '',
    lastTime: null
  });
  return React.useCallback(event => {
    if (event.key.length === 1 && event.key !== ' ') {
      const textCriteria = textCriteriaRef.current;
      const lowerKey = event.key.toLowerCase();
      const currentTime = performance.now();
      if (textCriteria.searchString.length > 0 && textCriteria.lastTime && currentTime - textCriteria.lastTime > TEXT_NAVIGATION_RESET_TIMEOUT) {
        textCriteria.searchString = lowerKey;
      } else if (textCriteria.searchString.length !== 1 || lowerKey !== textCriteria.searchString) {
        // If there is just one character in the buffer and the key is the same, do not append
        textCriteria.searchString += lowerKey;
      }
      textCriteria.lastTime = currentTime;
      callback(textCriteria.searchString, event);
    }
  }, [callback]);
}