Question

我有这段代码

let anchorRenderer: string => React.Component;  // line 658
if (link) {
    if (userAnchorRenderer) {
      anchorRenderer = userAnchorRenderer;  // line 661
    } else {
      anchorRenderer = (link: string) => <a className={styles.link} href={link}/>    // line 663
    }
}

...

// Usage of the function 
return <div>
    {anchorRenderer && anchorRenderer(link)})   
 </div>

但是我不能正确地声明类型。

在此版本中，出现以下错误：

Error:(663, 11) TS2322: Type 'P["anchorRenderer"]' is not assignable to type 'string'.
  Type '((link: string) => Component<{}, {}, any>) | undefined' is not assignable to type 'string'.
    Type 'undefined' is not assignable to type 'string'.
Error:(663, 11) TS2322: Type '(link: string) => Element' is not assignable to type 'string'.

如果我将变量声明更改为

let anchorRenderer: string => React.Component | undefined;

我得到了这个错误

Error:(658, 35) TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.

如何修复类型声明？

Answer 1

更改

let anchorRenderer: string => React.Component | undefined;

到

let anchorRenderer: (str: string) => React.Component | undefined;

您不能省略参数名称（https://github.com/Microsoft/TypeScript/issues/3693），也必须在类型声明中使用括号（与js箭头功能相反）。

Typescript中可为空的函数变量的正确类型是什么？

1 个答案: