const list =[ // a 班在今年的第1周打扫了3次卫生 { name :' a 班', count :3, week :1},{ name :' b 班', count :4, week :1},{ name :' c 班', count :5, week :2},{ name :' a 班', count :3, week :3},{ name :' b 班', count :4, week :3}求各班级打扫卫生的总数，在打扫卫生的周里，平均每周打扫了几次

根据给出的列表，我们可以使用循环和条件语句来计算各班级打扫卫生的总数和平均每周打扫次数。下面是一个示例的JavaScript代码：

const list = [
  { name: 'a班', count: 3, week: 1 },
  { name: 'b班', count: 4, week: 1 },
  { name: 'c班', count: 5, week: 2 },
  { name: 'a班', count: 3, week: 3 },
  { name: 'b班', count: 4, week: 3 }
];

// 计算各班级打扫卫生的总数
const totalCounts = {};
for (const item of list) {
  const { name, count } = item;
  if (totalCounts[name]) {
    totalCounts[name] += count;
  } else {
    totalCounts[name] = count;
  }
}

console.log('各班级打扫卫生的总数：', totalCounts);

// 计算平均每周打扫次数
const weeklyCounts = {};
const weeklyOccurrences = {};
for (const item of list) {
  const { name, count, week } = item;
  if (weeklyCounts[name]) {
    weeklyCounts[name] += count;
    weeklyOccurrences[name]++;
  } else {
    weeklyCounts[name] = count;
    weeklyOccurrences[name] = 1;
  }
}

const averageCounts = {};
for (const name in weeklyCounts) {
  averageCounts[name] = weeklyCounts[name] / weeklyOccurrences[name];
}

console.log('平均每周打扫次数：', averageCounts);

这段代码会输出以下结果：

各班级打扫卫生的总数： { a班: 6, b班: 8, c班: 5 }
平均每周打扫次数： { a班: 3, b班: 4, c班: 5 }

这样，你就得到了各班级打扫卫生的总数，以及在打扫卫生的周里平均每周打扫了几次。