TypeScript数组类型属性调用size报错问题求助

错误原因 #

你在Graph类的printData方法中访问this.nodes.size和this.edges.size报错，核心原因是数组类型没有size属性。你声明的nodes和edges是_Node[]、Edge[]数组，获取数组元素数量需要使用length属性，而size是Set、Map等集合类型专属的属性。

直接修复方案 #

将printData方法中的size替换为length即可解决报错：

// Graph.ts 中修改 printData 方法
printData() {
  const message =
    "This is a graph with " +
    this.nodes.length +
    " nodes and " +
    this.edges.length +
    " edges";
  console.log(message);
}

额外TypeScript代码优化 #

原代码存在类型模糊、类与接口未绑定等不规范问题，建议做以下优化以提升代码类型安全性：

1. 让_Node类实现对应接口并明确属性类型 #

// _Node.ts
interface _Node {
  data: Record<string, unknown>; // 替换any为更具体的类型，可根据业务需求调整
  neighbours: number[];
}

class _Node implements _Node {
  data: Record<string, unknown>;
  neighbours: number[];

  constructor(data: Record<string, unknown>) {
    this.data = { ...data };
    this.neighbours = [];
  }
}

export { _Node };

2. 优化Edge类的类型定义 #

// Edge.ts
interface Edge {
  start: number;
  end: number;
  data: Record<string, unknown>;
}

class Edge implements Edge {
  start: number;
  end: number;
  data: Record<string, unknown>;

  constructor(start: number, end: number, data: Record<string, unknown>) {
    this.start = start;
    this.end = end;
    this.data = { ...data };
  }
}

export { Edge };

3. 完善Graph类的类型绑定与代码简洁性 #

// Graph.ts
import { _Node } from "./_Node";
import { Edge } from "./Edge";

interface Graph {
  nodes: _Node[];
  edges: Edge[];
}

class Graph implements Graph {
  nodes: _Node[];
  edges: Edge[];

  constructor(nodes: _Node[], edges: Edge[]) {
    this.nodes = nodes;
    this.edges = edges;
    // this.printData();
  }

  printData() {
    // 使用模板字符串替代字符串拼接，代码更简洁
    const message = `This is a graph with ${this.nodes.length} nodes and ${this.edges.length} edges`;
    console.log(message);
  }
}

内容的提问来源于stack exchange，提问作者Indrajeet Haldar