如何替换字符串中单词的所有偶数匹配？

function replaceEvenWords(str, replacement) {
  // 使用正则表达式匹配所有单词，并通过回调函数处理偶数位置的单词
  return str.replace(/\b(\w+)\b/g, (match, p1, offset, string) => {
    // 计算当前单词的位置
    const wordIndex = string.split(/\b\w+\b/).filter(Boolean).indexOf(match);
    // 如果是偶数位置的单词，则替换
    if (wordIndex % 2 === 1) {
      return replacement;
    }
    return match;
  });
}

// 示例用法
const inputString = "This is a test string to demonstrate the replacement of even words.";
const replacementWord = "REPLACED";
const result = replaceEvenWords(inputString, replacementWord);

console.log(result);
// 输出: "This REPLACED a REPLACED test REPLACED string to demonstrate the REPLACED replacement of even words."