javascript - 减少数组函数的 typescript 错误 - "string' 不可分配给类型的参数

Question

我目前正在学习 typescript 并遇到了以下函数的 typescript 错误:

export interface WebspaceBackupArtifact {
    readonly date?: string;
    readonly name?: string | null;
    readonly path?: string | null;
    readonly type?: string | null;
}
 
interface WebspaceBackupArtifactExtended extends WebspaceBackupArtifact {
  size: string;
  type: string;
}

const selected = [] as WebspaceBackupArtifactExtended[],

const totalSize = (): number => {
return selected
        .filter(
          (artifact: WebspaceBackupArtifactExtended) =>
            artifact.type !== 'directory',
        )
        .reduce(
          (accumulator: number, artifact: WebspaceBackupArtifactExtended) =>
            accumulator + artifact.size,
          0,
        );
}

上述函数产生以下错误:

ERROR in /app/src/views/myfile.vue(394,11): No overload matches thiscall. Overload 1 of 3, '(callbackfn: (previousValue:WebspaceBackupArtifactExtended, currentValue:WebspaceBackupArtifactExtended, currentIndex: number, array:WebspaceBackupArtifactExtended[]) => WebspaceBackupArtifactExtended,initialValue: WebspaceBackupArtifactExtended):WebspaceBackupArtifactExtended', gave the following error. my-project| Argument of type '(accumulator: number, artifact:WebspaceBackupArtifactExtended) => string' is not assignable toparameter of type '(previousValue: WebspaceBackupArtifactExtended,currentValue: WebspaceBackupArtifactExtended, currentIndex: number,array: WebspaceBackupArtifactExtended[]) =>WebspaceBackupArtifactExtended'. my-project | Types ofparameters 'accumulator' and 'previousValue' are incompatible.my-project | Type 'WebspaceBackupArtifactExtended' is notassignable to type 'number'.

和

my-project | Overload 2 of 3, '(callbackfn: (previousValue:number, currentValue: WebspaceBackupArtifactExtended, currentIndex:number, array: WebspaceBackupArtifactExtended[]) => number,initialValue: number): number', gave the following error. my-project
| Argument of type '(accumulator: number, artifact:WebspaceBackupArtifactExtended) => string' is not assignable toparameter of type '(previousValue: number, currentValue:WebspaceBackupArtifactExtended, currentIndex: number, array:WebspaceBackupArtifactExtended[]) => number'. my-project |
Type 'string' is not assignable to type 'number'. my-project |
392 | ) my-project | 393 | .reduce( my-project| > 394 | (accumulator: number, artifact:WebspaceBackupArtifactExtended) => my-project | |
^ my-project | 395 | accumulator + artifact.size,my-project | 396 | 0, my-project | 397 |
);

为什么在我定义了类型之后它会抛出这些错误？我尝试更改此行:

(累加器:数字，工件:WebspaceBackupArtifactExtended)=>

到

(previousValue:WebspaceBackupArtifactExtended，currentValue:WebspaceBackupArtifactExtended)=>

但它仍然导致相同的错误消息...

Answer 1

您将 WebspaceBackupArtifactExtended.size 定义为 number 因此 accumulator + artifact.size 返回一个字符串。将 size 的定义更改为 number 可以修复错误。