我到达这里:
buyTicketData?.pricingOptions
这个错误:
[tsl] ERROR in /Applications/MAMP/htdocs/wp-content/plugins/tikex/tikexModule/components/BuyTicket/PricingOptionInvoiceItemsFormFieldsCheckboxes.tsx(280,25)
TS2532: Object is possibly 'undefined'.
如果 ?
的左侧未定义,为什么 ?
会包裹它,而不是?
以下是类型:
buyTicketData?: BuyTicketData;
export type BuyTicketData = {
pricingOptions?: PricingOptions;
}
export type PricingOptions = {
[optionId: string]: PricingOptionType;
};
export type PricingOptionType = {
invoiceItems?: InvoiceItems;
};
export type InvoiceItems = {
[invoiceItemId: string]: InvoiceItemData;
};
export type InvoiceItemData = {
defaultValue?: number;
};
这就是整个表达式
<select
value={
startPaymentIn?.invoiceItems?.[key] != undefined
? startPaymentIn?.invoiceItems?.[key] == 1
? "Igen"
: "Nem"
: startPaymentIn?.pricingOptionId &&
buyTicketData?.pricingOptions?.[ // <-- here
startPaymentIn!.pricingOptionId!
].invoiceItems[key]?.defaultValue != undefined
? startPaymentIn?.pricingOptionId &&
buyTicketData?.pricingOptions?.[
startPaymentIn!.pricingOptionId!
].invoiceItems[key]?.defaultValue == 1
? "Igen"
: "Nem"
: undefined
}
好的,找到解决方案:
value={
startPaymentIn?.invoiceItems?.[key] != undefined
? startPaymentIn?.invoiceItems?.[key] == 1
? "Igen"
: "Nem"
: buyTicketData?.pricingOptions?.[
startPaymentIn?.pricingOptionId ?? ""
]?.invoiceItems?.[key]?.defaultValue != undefined
? buyTicketData?.pricingOptions?.[
startPaymentIn?.pricingOptionId ?? ""
]?.invoiceItems?.[key]?.defaultValue == 1
? "Igen"
: "Nem"
: undefined
}
我只是不知道为什么这个丑陋的? ""
条件需要。
最佳答案
如果 a
为 undefined
,则 a.b
会抛出异常,而 a?.b
则解析为 undefined
。您仍然需要处理未定义
。
buyTicketData?.pricingOptions?.[startPaymentIn?.pricingOptionId]
决定
buyTicketData?.pricingOptions?.[undefined]
如果startPaymentIn
是未定义
。这会引发错误,因为 undefined
不能是键。
如果这个变量是必需的,更好的方法是在所有内容之前进行空检查,这样您就根本不需要?.
。
if(startPaymentIn)
{
//no need to use ?. on startPayment
}
关于javascript - 为什么我在这个可选链中收到 "Object is possibly ' undefined'"?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/70647673/