var dtime = '_deadtime';

/**
 * 设置本地缓存
 * k key
 * v value
 * t time
 */
function setStorage(k, v, t) {
  wx.setStorageSync(k, v);
  let seconds = parseInt(t);
  if (seconds > 0) {
    let timestamp = Date.parse(new Date());
    timestamp = timestamp / 1000 + seconds;
    wx.setStorageSync(k + dtime, timestamp + "");
  } else {
    wx.removeStorageSync(k + dtime);
  }
}

/**
 * 根据名称获取数据缓存
 * k key
 */
function getStorage(k, def) {
  let deadtime = parseInt(wx.getStorageSync(k + dtime));
  if (deadtime) {
    if (parseInt(deadtime) < Date.parse(new Date()) / 1000) {
      if (def) { 
        return def; 
      } else { 
        return; 
      }
    }
  }
  let res = wx.getStorageSync(k);
  if (res) {
    return res;
  } else {
    return def;
  }
}

/**
 * 根据名称删除指定本地缓存
 * k key
 */
function removeStorage(k) {
  wx.removeStorageSync(k);
  wx.removeStorageSync(k + dtime);
}

/**
 * 清空全部本地缓存
 */
function clearStorage() {
  wx.clearStorageSync();
}

// 模板语言转换
module.exports = {
  setStorage: setStorage,
  getStorage: getStorage,
  removeStorage: removeStorage,
  clearStorage: clearStorage
}

调用方式：

let testVal = '123456';
common.setStorage('test', testVal, 604800); // 设置缓存，缓存时间S
common.getStorage('test'); // 取缓存
common.removeStorage('test'); // 删除指定缓存
common.clearStorage(); // 删除全部