What is the procedure for obtaining a list of items with the second item marked as "true"?

Question

What is the procedure for obtaining a list of items with the second item marked as "true"?

Can you please provide guidance on how to iterate through a list of addresses (address object) where the object has the property "def" set to true? Here is an example response from an API request:

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

The initial approach I tried is as follows:

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

However, this code returns all addresses, not just the ones where "def" is true. The output includes: FB2A23D4-554E9,FA0EBFB496DA-C5465A8D,FA0434B496DA-C5465A8D

Additionally, I attempted a different approach:

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

Unfortunately, this code leads to an error message: Uncaught TypeError: Cannot read properties of undefined (reading 'address')

javascript

Answer 1

Answer №1

filter and map serve different purposes, and what you really need is a combination of both. While using map may have "worked," the issue was that the results were not filtered. First, apply filter to narrow down the data, then use map to reshape it as desired. Lastly, join the elements together and output the final outcome.

(Moreover, remember to use true instead of 'true' for filtering, since using === with a string won't yield the intended result.)

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

console.log(result);

On a side note... In this scenario, there is no need for idToLookFor. If result.def is true, you can simply return that value from the filter function.

Answer 2

filter and map serve different purposes, and what you really need is a combination of both. While using map may have "worked," the issue was that the results were not filtered. First, apply filter to narrow down the data, then use map to reshape it as desired. Lastly, join the elements together and output the final outcome.

(Moreover, remember to use true instead of 'true' for filtering, since using === with a string won't yield the intended result.)

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

console.log(result);

On a side note... In this scenario, there is no need for idToLookFor. If result.def is true, you can simply return that value from the filter function.

Answer 3

Answer №2

An error occurs when you fail to account for the scenario where def is not true

let targetItem = myArray.find((element) => {
  return element.def === true;
});
targetItem ? console.log(targetItem.address) : console.log("not found");

Answer 4

An error occurs when you fail to account for the scenario where def is not true

let targetItem = myArray.find((element) => {
  return element.def === true;
});
targetItem ? console.log(targetItem.address) : console.log("not found");

What is the procedure for obtaining a list of items with the second item marked as "true"?

Answer №1

Answer №2

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