javascript - 可选链接不起作用 : Cannot read property '0' of undefined

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已结束。此问题需要 debugging details .它目前不接受答案。

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关闭 2 年前。

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为什么可选链在这里不起作用？

.html

 {{userItemModel?.item?.priceList[0]?.sellerUrl}}

它显示了这个错误。

TypeError: Cannot read property '0' of undefined

"@angular/core": "~10.1.1",

"typescript": "~4.0.2"

 "priceList": [
                {
                    "amount": 14.5,
                    "currency": "USD",
                    "sellerUrl": "https://www.bay.com/itm/Lear-6910-/33372049",
                    "basePrice": 15,
                    "discount": 10
                }
            ],

更新

用例 1:

  Parser Error: Unexpected token [, expected identifier or keyword at column 33 
in [                    {{userItemModel?.item?.priceList?.[0]?.sellerUrl}}
                    ] in 

用例 2:

Parser Error: Unexpected token [, expected identifier or keyword at column 33 in [

                    {{userItemModel?.item?.priceList?.[0].sellerUrl}}
                ] in 

Answer 1

要正确链接数组访问，您应该使用 arr?.[index]:

var foo = {}
try{
  console.log(foo?.bar[0])
}
catch(e){
  console.log(e.message)
}
console.log(foo?.bar?.[0])

编辑:这是 known issue此时有 Angular 。