图中深度优先搜索中for / of和forEach之间有什么区别？

问题描述

当我尝试使用

for(const ele of adjacencyList[v]){
    if(!obj[ele]) return helper(ele);
}

代替

adjacencyList[v].forEach(neighbor => {
    if(!obj[neighbor]){
        return helper(neighbor);
    }    
})

为什么结果graphTraversal.dfs_recursion("A")不同？

我在Internet上搜索了for...of和forEach()之间的区别，但仍然没有明白这一点。有人可以向我解释吗？

我的原始代码如下：

// Build an undirected graph
class Graph {
    constructor(){
        this.adjacencyList = {};
    }

    addVertex(vtx) {
        if(!this.adjacencyList[vtx]) this.adjacencyList[vtx] = [];
        return this.adjacencyList;
    }

    addEdge(v1,v2){
        if(!(this.adjacencyList.hasOwnProperty(v1) && this.adjacencyList.hasOwnProperty(v2))) return "sorry but there is no vertex";
        else{
            this.adjacencyList[v1].push(v2);
            this.adjacencyList[v2].push(v1);
        }
    }  

    dfs_recursion(vtx){
        const arr = [],obj = {};
        const adjacencyList = this.adjacencyList;

        const helper = (v) => {
            if(!v) return null;
            arr.push(v);
            obj[v] = true;

            adjacencyList[v].forEach(neighbor => {
                if(!obj[neighbor]){
                    return helper(neighbor);
                }    
            })
        }
        helper(vtx);

        return arr;
    }
}

let graphTraversal = new Graph();
graphTraversal.addVertex("A");
graphTraversal.addVertex("B");
graphTraversal.addVertex("C");
graphTraversal.addVertex("D");
graphTraversal.addVertex("E");
graphTraversal.addVertex("F");
graphTraversal.addEdge("A","B");
graphTraversal.addEdge("A","C");
graphTraversal.addEdge("B","D");
graphTraversal.addEdge("C","E");
graphTraversal.addEdge("D","F");
graphTraversal.addEdge("E","F");

console.log(graphTraversal.dfs_recursion("A"));

解决方法

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