如何将值添加到agencyList[0].itemName？
export class SelectedItem {
id: number;
itemName: string;
isChecked: boolean;
}
agencyList: SelectedItem[] = [];
我正在try agencyList[0].itemName = 'agency1';，但收到错误:Cannot set properties of undefined (setting 'itemName')
您需要首先使用SelectedItem的实例来初始化agencyList[0]，如下所示
agencyList[0] = new SelectedItem();
agencyList[0].itemName = "agency1";
假设您只想在项目尚未初始化的情况下执行此操作:
if (!agencyList[0]) {
agencyList[0] = new SelectedItem();
}
agencyList[0].itemName = "agency1";
您可以使用nullish coalescing assignment将其压缩为一行代码:
(agencyList[0] ??= new SelectedItem()).itemName = 'agency1'