Question

当条件满足时，我无法停止函数以继续执行后续逻辑。如下代码所示，如果outstanding Balance substract reqPaidAmount小于0，函数应该停止在这个状态并向调用者响应相应的错误信息，但代码并没有在这个阶段停止，尽管我使用了return。

任何人或开发人员能否建议我在满足给定条件时停止继续执行此函数的最合适方法。

 items.map(async v => {
        try{
            const itemInfo = await OrderItemTransaction.findOne({
                where: { itemId: v.itemId },
                attributes: [
                    [db.Sequelize.literal('(OrderItem.unitPrice - SUM(paidAmount))'), 'outstandingBlc']
                ],
                include: [{
                    model: OrderItem,
                    attributes: ['id', 'unitPrice'],
                    on: {
                        'id': { [Op.eq]: db.sequelize.col('OrderItemTransaction.itemId') }
                    },
                    required: true
                }],
                raw: true
            });
            if (itemInfo['OrderItem.id'] == null) return void res.status(404).json({ error: "Invalid item Id" });
            const reqPaidAmount = v.paidAmount;
            const outstandingBalance = itemInfo.outstandingBlc;
            console.log(reqPaidAmount + "|" + outstandingBalance);
            if (outstandingBalance - reqPaidAmount < 0) {
                console.log("we're here 1");
                res.status(403).json({ error: `Cannot complete payment for ${v.itemId} because paid amount is ${reqPaidAmount} and outstanding balance is ${outstandingBalance}` })
                return;
            }
            else if (outstandingBalance < 0){
                console.log("we're here 2");
                res.status(403).json({error:`${v.itemId} has been paid by others`});
                return;
            }
        }
        catch(err){
            res.status(500).json({ error: err.message });
        }

当我尝试放置时，我不断收到此错误消息

return res.status(403).json({ error: `Cannot complete payment for ${v.itemId} because paid amount is ${reqPaidAmount} and outstanding balance is ${outstandingBalance}` });

(node:15856) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (_http_outgoing.js:518:11)
    at ServerResponse.header (C:\Users\jacob\Desktop\restAPI\node_modules\express\lib\response.js:771:10)
    at ServerResponse.send (C:\Users\jacob\Desktop\restAPI\node_modules\express\lib\response.js:170:12)
    at ServerResponse.json (C:\Users\jacob\Desktop\restAPI\node_modules\express\lib\response.js:267:15)
    at C:\Users\jacob\Desktop\restAPI\controllers\order.js:376:41
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
(node:15856) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI 
flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:15856) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Answer 1

如果您想要的结果是停止执行更多元素，请在使用 return 时将 forEach 与普通 for 循环进行比较；

const elem = await page.$(anySelector)
const parent = await elem.$('xpath=..')

第一个将产生 'run' 两次，而后者只产生一次。

Answer 2

Javascript 有时会容忍这样的事情，但是您是否注意到这一行

res.status(403).json({ error: Cannot complete payment for ${v.itemId} because paid amount is ${reqPaidAmount} and outstanding balance is ${outstandingBalance} })

缺少分号？

if-else 满足条件时停止执行

2 个答案: