Question

我是JavaScript的新手，并且立即面临JavaScript递归的问题。问题是，即使我将return语句放入函数的内部调用中，其值仍为undefine d。我希望下面的示例可以解释我的问题。

// from cable是JSON，其中可能包含嵌套的内部对象 // strand是简单的整数

来自电缆样本JSON：

{
   "ConnectionType":"StraightThrough",
   "TotalLength":18,
   "Bundles":[
      {
         "IsVisible":false,
         "Strands":[
            {
               "IsGrooved":true,
               "IsConnected":true,
               "ConductorOrdinal":1,
               "Ordinal":1,
               "PrimaryColor":"#0000FF",
               "Type":"Strand",
               "Username":"Fiber 1",
               "Description":"Fiber 1"
            },
            {
               "IsGrooved":true,
               "IsConnected":true,
               "ConductorOrdinal":2,
               "Ordinal":2,
               "PrimaryColor":"#FFA500",
               "Type":"Strand",
               "Username":"Fiber 2",
               "Description":"Fiber 2"
            },
            {
               "IsGrooved":true,
               "IsConnected":true,
               "ConductorOrdinal":3,
               "Ordinal":3,
               "PrimaryColor":"#008000",
               "Type":"Strand",
               "Username":"Fiber 3",
               "Description":"Fiber 3"
            },
            {
               "IsGrooved":false,
               "IsConnected":false,
               "ConductorOrdinal":4,
               "Ordinal":4,
               "PrimaryColor":"#A52A2A",
               "Type":"Strand",
               "Username":"Fiber 4",
               "Description":"Fiber 4"
            }
         ],
         "Ordinal":1,
         "Type":"Bundle",
         "Username":"-",
         "Description":"-"
      }
   ],
   "SuperType":"Conductor",
   "Fno":7200,
   "Fid":51008,
   "IsDefective":false,
   "HasGraphics":true,
   "Location":"ALBLPQ01",
   "NumberOfNodes":0,
   "Type":"Cable",
   "Username":"Fiber Cable",
   "Description":"Fiber Cable - Position  - 51008"
}

代码本身：

//conductor here is undefined
//from cable is JSON that may contains nested inner objects in there
//strand is simple integer number
let conductor = FindConductor(fromCable, position.FromFeature.Strand);



//I need to check "Strands" properties because there may be conductors along with bundle 
//Bundle can contains more conductors, so that's why I use recursive here

function FindConductor(item , ConductorOrdinal){
  if(item.hasOwnProperty('Strands')){
    item.Strands.forEach((strand)=>{
       if(strand.ConductorOrdinal === ConductorOrdinal){
         console.log('result!!');
         console.log(strand)
         return strand;
       }
    })
  }
  if(item.hasOwnProperty('Bundles')){
    for (let i = 0; i < item.Bundles.length; i++) {
      return FindConductor(item.Bundles[i], ConductorOrdinal);
    }
  }
}

问题是，对于下面提供了JSON的示例，它应返回6个匹配项。而且我可以在控制台6上看到正确的结果，但前提是我不会在递归调用之前放置 return 语句。如果我将返回语句作为示例，则我只会收到4个而不是6个匹配项。和以前一样，函数返回null。我是JavaScript的初学者，希望能获得明确的帮助来解释为什么会出现此问题。

递归函数即使返回自身也不返回值

0 个答案: