如何在不使用传统的 js 对象导航样式的情况下返回嵌套对象中的属性值？答案

【问题标题】：How do return the value of an attribute in a nested object without using the traditional js object navigation style?如何在不使用传统的 js 对象导航样式的情况下返回嵌套对象中的属性值？
【发布时间】：2021-06-11 00:37:54
【问题描述】：

例如，如何在不执行“tags.value”或“style.value”的情况下自动循环遍历下面对象中的所有“value”属性

[
  {
    "title": "Old Man's War",
    "author": {
      "name": "John Scalzi",
      "tags": [
        {
          "value": "American"
        }
      ]
    }
  },
  {
    "title": "The Lock Artist",
    "author": {
      "name": "Steve Hamilton",
      "tags": [
        {
          "value": "English"
        }
      "style": [
        {
          "value": "Italix"
        }
      ]
    }
  }
]

【问题讨论】：

标签： javascript node.js json search

【解决方案1】：

您是否要提取所有样式和标签的列表？一种直接的方法是通过reduce()、map() 组合

let attributes = data.reduce((b, a) => ({
    tags: [...b.tags, a.author.tags?.map(v => v.value) || []].flat(),
    styles: [...b.styles, a.author.style?.map(v => v.value) || []].flat() }), {tags:[], styles:[]})

输出：

{
  "tags": [
    "American",
    "English"
  ],
  "styles": [
    "Italix"
  ]
}

const data = [{
  "title": "Old Man's War",
  "author": {
    "name": "John Scalzi",
    "tags": [{
      "value": "American"
    }]
  }
}, {
  "title": "The Lock Artist",
  "author": {
    "name": "Steve Hamilton",
    "tags": [{
      "value": "English"
    }],
    "style": [{
      "value": "Italix"
    }]
  }
}]

// just the tag values

let attributes = data.reduce((b, a) => ({
    tags: [...b.tags, a.author.tags?.map(v => v.value) || []].flat(),
    styles: [...b.styles, a.author.style?.map(v => v.value) || []].flat() }), {tags:[], styles:[]})
console.log(attributes)

【讨论】：

@user16192387 - 这对您解决问题有帮助吗？如果是，请标记为答案。谢谢！

【解决方案2】：

//first,there is an error in your json.I assume it like this
const data = [
   {
      "title":"Old Man's War",
      "author":{
         "name":"John Scalzi",
         "tags":[
            {
               "value":"American"
            }
         ]
      }
   },
   {
      "title":"The Lock Artist",
      "author":{
         "name":"Steve Hamilton",
         "tags":[
            {
               "value":"English"
            }
         ],
         "style":[
            {
               "value":"Italix"
            }
         ]
      }
   }
]

for(const top of data){
  if(typeof top == 'object'){
    for(const second_key in top){
      const second = top[second_key]
      if(typeof second == 'object'){
        for(const third_key in second){
          const third = second[third_key]
          if(Array.isArray(third)){
            for(const fourth of third){
              document.write(fourth['value']+"<br>")
            }
          }
        }
      }
    }
  }
}

//this is another solution
const data = [
   {
      "title":"Old Man's War",
      "author":{
         "name":"John Scalzi",
         "tags":[
            {
               "value":"American"
            }
         ]
      }
   },
   {
      "title":"The Lock Artist",
      "author":{
         "name":"Steve Hamilton",
         "tags":[
            {
               "value":"English"
            }
         ],
         "style":[
            {
               "value":"Italix"
            }
         ]
      }
   }
]

function lookForValue(obj){
  if(obj.hasOwnProperty('value')){
    document.write(obj['value']+"<br>")
    return
  }
  if(typeof obj == 'object'){
    for(const key in obj){
      lookForValue(obj[key])
    }
  }
  if(Array.isArray(obj)){
    for(const item in obj){
      lookForValue(item)
    }
  }
}

lookForValue(data)

【讨论】：