string, index: number, ...

Question

In you type definition you declare that

is optional by adding the identifier

export interface LineChartProps {
     ...
    yAxesTicksMin?: number,
    yAxesTicksMax?: number,
    yAxesTicksCallback?: (value: number | string, index: number, values: number[] | string[]) => string | number | null | undefined
}

. Consequently TypeScript will compile this as yAxesTicksCallback the latter which causes the error when you're typecasting it to the function type. There's a bunch of ways to resolve this and it's a bit hard to advise on the best one without further context–but the first thing I'd investigate is if it's possible to remove the

...
yAxes: [{
  ticks: {
    min: yAxesTicksMin as number,
    max: yAxesTicksMax as number,
    stepSize: 1,
    callback: yAxesTicksCallback as (value: number | string, index: number, values: number[] | string[]) => string | number | null | undefined,
},
...

from the interface, this would allow you to remove the typecasting as well. I think this is nice because usually when I implement a typecast, I later find out that I was just being lazy and could structure my code in a better way. (使用Chart.js)TypeError: undefined is not a function

我得到了以下接口。callback然后在ChartJS对象中 "填充 "我的图表组件，我得到了一个变量

来代替回调。

问题就在这里开始了 当我定义 "变量为类型 "时，它抛出了以下错误。

Answer 1

在原来的界面（ChartJs界面）中也有同样的类型。yAxesTicksCallback谢谢，我得到的接口如下：export interface LineChartProps { ...? () => ... | undefined ?我得到了以下接口： export interface LineChartProps { ... yAxesTicksMin?: number, yAxesTicksMax?: number, yAxesTicksCallback?