Question

块中有问题 - “类型'未定义'无法转换为类型'T'”错误：

  removeItem(key: string) {
  this.map[key] = undefined as T ; }

//代码

class PrintMap <T> {
private map : { [key: string] : T } = {};

setItem(key : string, item : T) {
   this.map[key] = item;
}
getItem(key : string) {
    return this.map[key];
}
clear() {
    this.map = {};
}
  removeItem(key: string) {
      this.map[key] = undefined as T ;
  }
print() {
    for (let key in this.map) {
        console.log(key , this.map[key]);
    }
}

Answer 1

您只需将其转换为any即可绕过类型检查：

this.map[key] = undefined as any;

Answer 2

T和undefined是不同的类型。

您只需使用delete this.map[key]删除该条目。

类型'undefined'无法转换为'T'类型

2 个答案: