javascript在嵌套对象/数组中按值查找

Posted 2023-02-19

【中文标题】javascript在嵌套对象/数组中按值查找

【英文标题】：javascript find by value deep in a nested object/array

【发布时间】：2018-01-02 07:50:41

【问题描述】：

你好，我在函数中返回对象时遇到问题，假设我有一个对象：

var elements = [
    "fields": null,
    "id_base": "nv_container",
    "icon": "layout",
    "name": "container",
    "is_container": true,
    "elements" : [
        //another elements set here
    ]
, 

    "id_base": "novo_example_elementsec",
    "name": "hello",
    "icon": "edit",
    "view": 
];

我想要的是一个可以找到具有特定键和值的对象的函数（在纯 javascript 中），并且我创建了一个函数，但它只是不能正常工作？ ，我的功能：

function findNested(obj, key, value) 
    //Early return
    if (obj[key] === value) 
        console.log( 'before return' ); //until here . its fine
        return obj; //not working
     else 
        for (var i = 0, len = Object.keys(obj).length; i <= len; i++) 
            if (typeof obj[i] == 'object') 
                this.findNested(obj[i] , key, value);
            
        
    

我只是看不出我做错了什么？ 谢谢。

【参考方案1】：

在进行递归调用后，您错过了返回。如果在递归后找到对象，您需要继续将该结果冒泡（通过返回它）。正如@scott-marcus 所指出的，您还应该使用i < len（而不是i <= len）。

var elements = [
    "fields": null,
    "id_base": "nv_container",
    "icon": "layout",
    "name": "container",
    "is_container": true,
    "elements": [
      //another elements set here
    ]
  ,
  
    "id_base": "novo_example_elementsec",
    "name": "hello",
    "icon": "edit",
    "view": 
  
];

function findNested(obj, key, value) 
  // Base case
  if (obj[key] === value) 
    return obj;
   else 
    for (var i = 0, len = Object.keys(obj).length; i < len; i++) 
      if (typeof obj[i] == 'object') 
        var found = this.findNested(obj[i], key, value);
        if (found) 
          // If the object was found in the recursive call, bubble it up.
          return found;
        
      
    
  


console.log(findNested(elements, "icon", "layout")); // returns object
console.log(findNested(elements, "icon", "edit")); // returns object
console.log(findNested(elements, "foo", "bar")); // returns undefined

【讨论】：

非常感谢@smarx，这就是我想要的，我找了6个小时的解决方案，再次感谢

【参考方案2】：

仅供未来的读者阅读。除了 @user94559 的回答。

更通用的方法是遍历键而不是索引，否则不会找到所有嵌套属性。 在进行递归调用之前检查obj[k] 以忽略空值

var elements = [
    "fields": null,
    "id_base": "nv_container",
    "icon": "layout",
    "name": "container",
    "is_container": true,
    "elements": [
      "icon": "nested"
    ]
  ,
  
    "id_base": "novo_example_elementsec",
    "name": "hello",
    "icon": "edit",
    "view": 
  
];

function findNested(obj, key, value) 

  // Base case
  if (obj[key] === value) 
    return obj;
   else 
    var keys = Object.keys(obj); // add this line to iterate over the keys

    for (var i = 0, len = keys.length; i < len; i++) 
      var k = keys[i]; // use this key for iteration, instead of index "i"

      // add "obj[k] &&" to ignore null values
      if (obj[k] && typeof obj[k] == 'object') 
        var found = findNested(obj[k], key, value);
        if (found) 
          // If the object was found in the recursive call, bubble it up.
          return found;
        
      
    
  


console.log(findNested(elements, "icon", "layout")); // returns object
console.log(findNested(elements, "icon", "edit")); // returns object
console.log(findNested(elements, "foo", "bar")); // returns undefined

// this will work now
console.log(findNested(elements, "icon", "nested")); // returns object