$cookies.set(keyName, value[, expireTimes[, path[, domain[, secure]]]])   //return this

中括号代表可选参数

上面一行等于下面五行：

$cookies.set(keyName, value)   //return this

$cookies.set(keyName, value,expireTimes)   //return this

$cookies.set(keyName, value, expireTimes, path)   //return this

$cookies.set(keyName, value, expireTimes, path, domain)   //return this

$cookies.set(keyName, value, expireTimes, path, domain, secure)   //return this