Ways to verify the presence of a key within an array of objects

Question

Ways to verify the presence of a key within an array of objects

I'm on a mission to determine whether a specified key exists in an array of objects. If the key value is present, I need to return true; otherwise, false.

I enter the key into a text box as input and then attempt to check if it exists in the array of objects, but so far, no luck.

Here's what I've attempted:

code:

var obj = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}]

var val = $("input[name='type_ahead_input']").val();

if (obj[val]) {
    console.log('exists');
} else {
    console.log('does not exist');
}

If I input 'the carribean', which does exist in the object array, it still displays 'does not exist' in the console output.

How can I troubleshoot and fix this issue?

javascript arrays

Answer 1

Answer №1

To determine if there are objects in the array that contain a specific key, you can filter the array and only return the objects that have the desired key. If the resulting array has a length greater than zero, it indicates that there are elements with that key present.

var obj = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}];

var val = "the carribean";

var exists = obj.filter(function (o) {
  return o.hasOwnProperty(val);
}).length > 0;

if (exists) {
    console.log('exists');
} else {
    console.log('does not exist');
}

If the array contains objects with the desired key, regardless of whether the value is undefined or null, this code will output true.

Answer 2

To determine if there are objects in the array that contain a specific key, you can filter the array and only return the objects that have the desired key. If the resulting array has a length greater than zero, it indicates that there are elements with that key present.

var obj = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}];

var val = "the carribean";

var exists = obj.filter(function (o) {
  return o.hasOwnProperty(val);
}).length > 0;

if (exists) {
    console.log('exists');
} else {
    console.log('does not exist');
}

If the array contains objects with the desired key, regardless of whether the value is undefined or null, this code will output true.

Answer 3

Answer №2

Checking for the existence of a key in an object can be done using typeof.

if (typeof obj[0][val] !== "undefined" ) {
    console.log('exists');
} else {
    console.log('does not exist');
}

It's important to note that the index 0 is used because the object being checked is element 0 of the array obj.

Here is a fiddle:

var obj = [{
"7364234":"hsjd",
"tom and jerry":"dsjdas",
"mickey mouse":"kfjskdsad",
"popeye the sailor man":"alkdsajd",
"the carribean":"kasjdsjad"
}];

if ( typeof obj[0]["the carribean"] !== 'undefined' ) {
console.log('exists');
} else {
console.log('does not exist');
}

As suggested by Cristy below, another way to check for key existence is using obj[0][val] === undefined

You can also try this:

var obj = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}];

var val = "7364234";

if ( val in obj[0] ) {
    console.log('exists');
} else {
    console.log('does not exist');
}

Answer 4

Checking for the existence of a key in an object can be done using typeof.

if (typeof obj[0][val] !== "undefined" ) {
    console.log('exists');
} else {
    console.log('does not exist');
}

It's important to note that the index 0 is used because the object being checked is element 0 of the array obj.

Here is a fiddle:

var obj = [{
"7364234":"hsjd",
"tom and jerry":"dsjdas",
"mickey mouse":"kfjskdsad",
"popeye the sailor man":"alkdsajd",
"the carribean":"kasjdsjad"
}];

if ( typeof obj[0]["the carribean"] !== 'undefined' ) {
console.log('exists');
} else {
console.log('does not exist');
}

As suggested by Cristy below, another way to check for key existence is using obj[0][val] === undefined

You can also try this:

var obj = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}];

var val = "7364234";

if ( val in obj[0] ) {
    console.log('exists');
} else {
    console.log('does not exist');
}

Answer 5

Answer №3

If you're looking to determine the existence of a key and retrieve its value from an array, I recommend using Array.some() along with Array.find(). Here's some code showcasing this approach:

let arr = [{"foo": 1}, {"bar":2}];

function isKeyInArray(array, key) { 
  return array.some(obj => obj.hasOwnProperty(key)); 
}

function getValueFromKeyInArray(array, key) { 
  return array.find(obj => obj[key])?.[key]; 
}

console.log(isKeyInArray(arr, "foo"), isKeyInArray(arr, "bar"), isKeyInArray(arr, "baz"));
console.log(getValueFromKeyInArray(arr, "foo"), getValueFromKeyInArray(arr, "bar"), getValueFromKeyInArray(arr, "baz"));

Answer 6

If you're looking to determine the existence of a key and retrieve its value from an array, I recommend using Array.some() along with Array.find(). Here's some code showcasing this approach:

let arr = [{"foo": 1}, {"bar":2}];

function isKeyInArray(array, key) { 
  return array.some(obj => obj.hasOwnProperty(key)); 
}

function getValueFromKeyInArray(array, key) { 
  return array.find(obj => obj[key])?.[key]; 
}

console.log(isKeyInArray(arr, "foo"), isKeyInArray(arr, "bar"), isKeyInArray(arr, "baz"));
console.log(getValueFromKeyInArray(arr, "foo"), getValueFromKeyInArray(arr, "bar"), getValueFromKeyInArray(arr, "baz"));

Answer 7

Answer №4

To determine if a specific key exists in any of the objects within an array, you must iterate through each object's keys.

var objArr = [{
  "7364234": "hsjd",
  "tom and jerry": "dsjdas",
  "mickey mouse": "kfjskdsad",
  "popeye the sailor man": "alkdsajd",
  "the carribean": "kasjdsjad"
}]

const contains = (string) =>
  objArr.findIndex(
    // Is the string part of the object keys?
    obj => Object.keys(obj).includes(string)
  ) !== -1

console.log(contains('the carribean'))
console.log(contains('spaghetti'))

Answer 8

To determine if a specific key exists in any of the objects within an array, you must iterate through each object's keys.

var objArr = [{
  "7364234": "hsjd",
  "tom and jerry": "dsjdas",
  "mickey mouse": "kfjskdsad",
  "popeye the sailor man": "alkdsajd",
  "the carribean": "kasjdsjad"
}]

const contains = (string) =>
  objArr.findIndex(
    // Is the string part of the object keys?
    obj => Object.keys(obj).includes(string)
  ) !== -1

console.log(contains('the carribean'))
console.log(contains('spaghetti'))

Answer 9

Answer №5

The reason for the issue is due to having an array of objects [{...},{...}] instead of just a single object {...}. To resolve this, you can either switch to using a single object with your test or utilize the Array.find method to check if an object with the property val exists in your array. Here's an example:

var objArr = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}]

let val = $("input[name='type_ahead_input']").val();

var existingObj = objArr.find(function(element) {
  return typeof element[val] !== 'undefined';
});

if (existingObj[val]) {
console.log('was found');
} else {
console.log('not-found');

For more information, refer to: https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Objets_globaux/Array/find

Answer 10

The reason for the issue is due to having an array of objects [{...},{...}] instead of just a single object {...}. To resolve this, you can either switch to using a single object with your test or utilize the Array.find method to check if an object with the property val exists in your array. Here's an example:

var objArr = [{
    "7364234":"hsjd",
    "tom and jerry":"dsjdas",
    "mickey mouse":"kfjskdsad",
    "popeye the sailor man":"alkdsajd",
    "the carribean":"kasjdsjad"
}]

let val = $("input[name='type_ahead_input']").val();

var existingObj = objArr.find(function(element) {
  return typeof element[val] !== 'undefined';
});

if (existingObj[val]) {
console.log('was found');
} else {
console.log('not-found');

For more information, refer to: https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Objets_globaux/Array/find

Answer 11

Answer №6

To retrieve the specific object from the array, you will need to access it using the syntax obj[0][val]

var processData = function() {
  var obj = [{
    "7364234": "hsjd",
    "tom and jerry": "dsjdas",
    "mickey mouse": "kfjskdsad",
    "popeye the sailor man": "alkdsajd",
    "the carribean": "kasjdsjad"
  }];

  var val = $("input[name='type_ahead_input']").val();
  console.log(val);
  if (obj[0][val]) {
    console.log('Object exists');
  } else {
    console.log('Object does not exist');
  }
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<input name="type_ahead_input" value="" onkeyup="processData()">

Answer 12

To retrieve the specific object from the array, you will need to access it using the syntax obj[0][val]

var processData = function() {
  var obj = [{
    "7364234": "hsjd",
    "tom and jerry": "dsjdas",
    "mickey mouse": "kfjskdsad",
    "popeye the sailor man": "alkdsajd",
    "the carribean": "kasjdsjad"
  }];

  var val = $("input[name='type_ahead_input']").val();
  console.log(val);
  if (obj[0][val]) {
    console.log('Object exists');
  } else {
    console.log('Object does not exist');
  }
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<input name="type_ahead_input" value="" onkeyup="processData()">

Answer 13

Answer №7

One of the simplest solutions, in my opinion, is provided by @E. Sundin. In my own scenario, I achieved the desired outcome using the following approach...

let person = { 
    id: 2, 
    name: "jack", 
    age: 54, temp: 2323
}

if(!Object.keys(person).includes('id')) throw new BadRequest("Id was missing!");

If you're dealing with an array of objects created through a loop...

if(!person.every(elm => Object.keys(person).includes('id')) throw new BadRequest("Id was missing!");

This should hopefully get the job done.

Answer 14

One of the simplest solutions, in my opinion, is provided by @E. Sundin. In my own scenario, I achieved the desired outcome using the following approach...

let person = { 
    id: 2, 
    name: "jack", 
    age: 54, temp: 2323
}

if(!Object.keys(person).includes('id')) throw new BadRequest("Id was missing!");

If you're dealing with an array of objects created through a loop...

if(!person.every(elm => Object.keys(person).includes('id')) throw new BadRequest("Id was missing!");

This should hopefully get the job done.

Answer 15

Answer №8

Check out this code snippet:

let students = [{ firstName:'John' }, { email:'<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="364d4e5b48515a7d77717c7b39747775">[email protected]</a>' }, { grade: 'A' }]

const hasEmail = students.some(item => item.hasOwnProperty('email'))

console.log('Email found in array: ', hasEmail);

Answer 16

Check out this code snippet:

let students = [{ firstName:'John' }, { email:'<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="364d4e5b48515a7d77717c7b39747775">[email protected]</a>' }, { grade: 'A' }]

const hasEmail = students.some(item => item.hasOwnProperty('email'))

console.log('Email found in array: ', hasEmail);

Answer 17

Answer №9

    Using the Array.find() method helps find a specific key within an array of objects and returns true or false.

This is a straightforward way to verify the existence of a key in an array of objects.

Answer 18

    Using the Array.find() method helps find a specific key within an array of objects and returns true or false.

This is a straightforward way to verify the existence of a key in an array of objects.

Ways to verify the presence of a key within an array of objects

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

Answer №9

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