Typescript version：2.8.3，请考虑以下代码片段
s.zipWithIndex2 {
case (a, b) => (a + "2", b + 2)
}
我收到编译时错误，例如import axios from "axios";
import { Component } from "react";
import * as React from "react";
interface ICustomer {
id: number
firstName: string
lastName: string
}
interface IState {
customers: ICustomer[]
}
class AllCustomers extends Component<{}, IState> {
public state = {
customers: []
}
public componentDidMount() {
axios.get<ICustomer[]>(`http://localhost:8080/customers`)
.then(resp => this.setState({customers: resp.data}))
}
public render() {
const {customers} = this.state;
return (
<table>
{
customers.map(customer => (
<tr key={customer.id}>
<td>{customer.firstName}</td>
<td>{customer.lastName}</td>
</tr>
))
}
</table>
)
}
}
不是customer.id类型的字段
不知何故...... never的类型隐含为this.state.customer，这是错误的。如何将空数组作为初始值而不是可赋值数组类型的有效实例？
答案 0 :(得分：7)
这很愚蠢，但在为state使用ES7类属性时，您需要也键入它。
public state: IState = {
customers: []
}
如果您实例化state“经典”方式
constructor(props) {
super(props)
this.state = { customers: [] }
}
你不需要这个额外的步骤