如何阅读TypeScript的复杂interface?-灵析社区
MastFancy看到一个interface的声明，非常复杂： interface PromiseLike { /** * Attaches callbacks for the resolution and/or rejection of the Promise. * @param onfulfilled The callback to execute when the Promise is resolved. * @param onrejected The callback to execute when the Promise is rejected. * @returns A Promise for the completion of which ever callback is executed. */ then(onfulfilled?: ((value: T) => TResult1 | PromiseLike) | undefined | null, onrejected?: ((reason: any) => TResult2 | PromiseLike) | undefined | null): PromiseLike; } 1、这个很难看懂，请问一下，应该如何学习这个定义呢? 是否可以拆分一点一点地学到它的含义？ 2、需要带着什么样的思路才能去看懂，从想要定义它的目的去阅读吗？
ApplePro最简单的方法是,写实际的例子去进行对比,当然前提是熟悉 promise 怎么使用。
type IsEqual = T1 extends T2 ? (() => G extends T1 ? 1 : 2) extends () => G extends T2 ? 1 : 2 ? true : false : false
type AnyIsEqual = T1 extends T2 ? IsEqual extends true ? true : never : never
type BrowserNativeObject = Date | FileList | File
type Primitive = null | undefined | string | number | boolean | symbol | bigint
type PathImpl = V extends Primitive | BrowserNativeObject ? `${K}` : true extends AnyIsEqual ? `${K}` : `${K}` | `${K}.${PathInternal}`
type TupleKeys> = Exclude
type ArrayKey = number
type PathInternal = T extends ReadonlyArray ? IsTuple extends true ? {
[K in TupleKeys]-?: PathImpl;
}[TupleKeys] : PathImpl : {
[K in keyof T]-?: PathImpl;
}[keyof T]
type Path = T extends any ? PathInternal : never
这个例子看起来就非常复杂,但是如果写一个例子放上去,很容易就知道这是做什么,如果不写例子估计看半天都不知道干什么的