Question 289169 in Javascript Question posted in
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Javascript – How to get a list of objects where the second object has the status ''true'?

Please tell me. There is an Api request and in response I receive an array of the form:

{
  "status": true,
  "rspa": [
    {
      "address": "FB2A23D4-554E9",
      "def": false,
      "tk": false
    },
    {
      "address": "FA0EBFB496DA-C5465A8D",
      "def": true,
      "tk": false
    },
    {
      "address": "FA0434B496DA-C5465A8D",
      "def": true,
      "tk": false
    }
  ]
}

How to loop through a list of addresses (address object) where the object is "def": true?

myArray = data.rspa
var addrs = myArray.map(function(elem){
   return elem.address;
   }).join(",");
   console.log(addrs);

It works but displays all addresses. Result FB2A23D4-554E9,FA0EBFB496DA-C5465A8D,FA0434B496DA-C5465A8D

myArray = data.data.rspa
 var idToLookFor = 'true';
 var foundObject = myArray.filter(function(item) {
   return item.def === idToLookFor;
 })[0].address;
console.log(foundObject.address);
});

Gives an error message: Uncaught TypeError: Cannot read properties of undefined (reading ‘address’)

Tags:

3

Answers


  1. 0

    filter and map do two different things, and what you want is a combination of both. When you used map it "worked", except the results weren’t filtered. Just filter them first, then map them into the structure you want. Then join and output the result.

    (Additionally, you want to use true instead of 'true' as the value to filter on, otherwise comparing with === won’t return anything.)

    var data = {
  "status": true,
  "rspa": [
    {
      "address": "FB2A23D4-554E9",
      "def": false,
      "tk": false
    },
    {
      "address": "FA0EBFB496DA-C5465A8D",
      "def": true,
      "tk": false
    },
    {
      "address": "FA0434B496DA-C5465A8D",
      "def": true,
      "tk": false
    }
  ]
};

var myArray = data.rspa;
var idToLookFor = true;

var result = myArray.filter(function(item) {
  return item.def === idToLookFor;
}).map(function(elem){
  return elem.address;
}).join(",");

console.log(result);

    As an aside… You don’t even need idToLookFor in this case. If result.def is true then you can just return that value from the filter callback.

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  2. 0

    simply use Array.prototype.reduce() method…

    const
  data = 
    { status: true
    , rspa: 
      [ { address: 'FB2A23D4-554E9',        def: false, tk: false } 
      , { address: 'FA0EBFB496DA-C5465A8D', def: true,  tk: false } 
      , { address: 'FA0434B496DA-C5465A8D', def: true,  tk: false } 
    ] } 
, result =
    data.rspa.reduce( (r,{address,def}) =>
      {
      if (def) r.push(address);
      return r;
      },[]).join(',')
  ;
console.log(result);
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  3. 0

    You have an error because you don’t handle the case where def is false

    var foundObject = myArray.find(function(item) {
  return item.def === true;
});
foundObject ? console.log(foundObject.adress) : console.log("not found");
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