JavaScript - 使用键数组从嵌套对象中检索值 [英] JavaScript - retrieve value from nested object, using array of keys

问题描述

如何使用键数组从嵌套对象中获取值？

  //我的示例对象
 var obj = {
类型：购买，
类别：公寓，
类别选项：{
公寓：{
楼层：{
类型：数字，
值：null，
占位符：总楼层
}，
}，
}，
} 
 var keysArray = [value，floors，apartment，categoryOptions] 
  

我尝试使用 array.reduceRight 实现这一目标但无法使其发挥作用。

这是我试过的：

  var roadToValue = keysArray.reduceRight（
 function（previousValue，currentValue）{
 return previousValue +[+ currentValue +]; 
} 
）; 
 //上面的函数会产生一个单独的字符串，比如
 //categoryOptions [apartment] [floors] [value]
 //哪个off-course不能用作对象键
 //和obj [roadToValue]导致'undefined'
  

有没有办法如此我可以在这里获得传递给obj的正确密钥吗？

解决方案

你绝对可以使用 reduceRight 为此。问题是您创建了一个字符串，但是您需要将对象作为 initialValue 传递并使用方括号括号：

< pre class =snippet-code-js lang-js prettyprint-override> var obj = {type：Purchase，category：Apartment，categoryOptions：{apartment ：{floor：{type：number，value：null，placeholder：Total Floors}}}} var keysArray = [value，floors，apartment， categoryOptions] var value = keysArray.reduceRight（（r，e）=> r [e] || r，obj）console.log（value）

How can I get a value from a nested object, using an array of keys?

// my sample object
var obj = {
    type            : "Purchase",
    category        : "Apartment",
    categoryOptions : {
       apartment : {
           floors    : {
               type        : "number",
               value       : null,
               placeholder : "Total Floors"
           },
       },
    },
}
var keysArray = ["value", "floors", "apartment", "categoryOptions"]

I tried to use array.reduceRight to achieve this but could not make it work.

here is what I've tried :

var roadToValue = keysArray.reduceRight(
    function(previousValue, currentValue){
        return previousValue + "[" + currentValue + "]" ;
    }
);
// above function results in a single string like 
// "categoryOptions[apartment][floors][value]" 
// which off-course can't be used as object key
// and obj[roadToValue] results in 'undefined'

is there any way so I can get the proper key to pass to obj here?

解决方案

You definitely can use reduceRight for this. The problem is that you created a string, however you need to pass your object as initialValue and use the squared bracket notation:

var obj = {"type":"Purchase","category":"Apartment","categoryOptions":{"apartment":{"floors":{"type":"number","value":null,"placeholder":"Total Floors"}}}}
var keysArray = ["value", "floors", "apartment", "categoryOptions"]

var value = keysArray.reduceRight((r, e) => r[e] || r, obj)
console.log(value)

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