Ggtcf

Is it unprofessional to ask if a job posting on GlassDoor is real?

Are the number of citations and number of published articles the most important criteria for a tenure promotion?

Fencing style for blades that can attack from a distance

How do we improve the relationship with a client software team that performs poorly and is becoming less collaborative?

How can I make my BBEG immortal short of making them a Lich or Vampire?

How did the USSR manage to innovate in an environment characterized by government censorship and high bureaucracy?

Why are 150k or 200k jobs considered good when there are 300k+ births a month?

What defenses are there against being summoned by the Gate spell?

What are the differences between the usage of 'it' and 'they'?

In Japanese, what’s the difference between “Tonari ni” (となりに) and “Tsugi” (つぎ)? When would you use one over the other?

Writing rule stating superpower from different root cause is bad writing

What does it mean : "Canonical representative of Sbox is 0123468A5BCF79DE"? and How can we calculate this representative for Sbox?

Why do falling prices hurt debtors?

Theorems that impeded progress

Test whether all array elements are factors of a number

How to write a macro that is braces sensitive?

Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground?

Languages that we cannot (dis)prove to be Context-Free

What are these boxed doors outside store fronts in New York?

Dragon forelimb placement

Is it important to consider tone, melody, and musical form while writing a song?

LaTeX closing $ signs makes cursor jump

How is the claim "I am in New York only if I am in America" the same as "If I am in New York, then I am in America?

What does it mean to describe someone as a butt steak?

How to find if object inside array is NOT empty?

How do I remove a property from a JavaScript object?How do I check if an array includes an object in JavaScript?How to append something to an array?How do I redirect to another webpage?How do I test for an empty JavaScript object?Sort array of objects by string property valueHow do I empty an array in JavaScript?How to check if an object is an array?How do I remove a particular element from an array in JavaScript?How to use foreach with array in JavaScript?

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty height:90px;width:728px;box-sizing:border-box;

0

Say I have an array, like so:

arr = [, , , ]

I want to be able to know the length of the array, only counting objects within in it that have at least one property.

[, name: "Derby County", odds: 2, , ] // 1

[, name: "Derby County", odds: 2, name: "Fullham", odds: 3 ,] // 2

How do I achieve this?

javascript arrays json

share|improve this question

edited Mar 9 at 3:22

A7DC

asked Mar 9 at 2:21

A7DCA7DC

5081621

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Object.keys(obj).length will yield a non-zero result when there's at least one iterable, non-inherited property.
  
  – ziggy wiggy
  Mar 9 at 2:27
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  detect when something is added this has more than one way to interpret it, with quite different solutions
  
  – André Werlang
  Mar 9 at 2:41
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You're right @AndréWerlang I'll update OP now, thank you
  
  – A7DC
  Mar 9 at 2:52
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I've updated the OP, hopefully that's clearer?
  
  – A7DC
  Mar 9 at 2:56
  

  
  
  
  

add a comment | 

0

Say I have an array, like so:

arr = [, , , ]

I want to be able to know the length of the array, only counting objects within in it that have at least one property.

[, name: "Derby County", odds: 2, , ] // 1

[, name: "Derby County", odds: 2, name: "Fullham", odds: 3 ,] // 2

How do I achieve this?

javascript arrays json

share|improve this question

edited Mar 9 at 3:22

A7DC

asked Mar 9 at 2:21

A7DCA7DC

5081621

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Object.keys(obj).length will yield a non-zero result when there's at least one iterable, non-inherited property.
  
  – ziggy wiggy
  Mar 9 at 2:27
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  detect when something is added this has more than one way to interpret it, with quite different solutions
  
  – André Werlang
  Mar 9 at 2:41
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You're right @AndréWerlang I'll update OP now, thank you
  
  – A7DC
  Mar 9 at 2:52
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I've updated the OP, hopefully that's clearer?
  
  – A7DC
  Mar 9 at 2:56
  

  
  
  
  

add a comment | 

Say I have an array, like so:

arr = [, , , ]

I want to be able to know the length of the array, only counting objects within in it that have at least one property.

[, name: "Derby County", odds: 2, , ] // 1

[, name: "Derby County", odds: 2, name: "Fullham", odds: 3 ,] // 2

How do I achieve this?

javascript arrays json

share|improve this question

edited Mar 9 at 3:22

A7DC

asked Mar 9 at 2:21

A7DCA7DC

5081621

arr = [, , , ]

[, name: "Derby County", odds: 2, , ] // 1

[, name: "Derby County", odds: 2, name: "Fullham", odds: 3 ,] // 2

share|improve this question

edited Mar 9 at 3:22

A7DC

asked Mar 9 at 2:21

A7DCA7DC

5081621

share|improve this question

edited Mar 9 at 3:22

A7DC

asked Mar 9 at 2:21

A7DCA7DC

5081621

asked Mar 9 at 2:21

A7DCA7DC

5081621

asked Mar 9 at 2:21

A7DCA7DC

5081621

2 Answers
2

active

oldest

votes

1

arr.filter(x => Object.keys(x).length).length

As explained in other answers, Object.keys() returns property names from a given object. The inner .length is a shortcut to filter only items that have at least one property. The outer .length tells how many objects fit the description.

UPDATE:

The [].filter() method takes a function that returns a thruthy/falsy value. A number greater than 0 is thruthy, so it's the same as .length !== 0.

The assumption here is that any element contained in the array is non-null. Under this assumption it makes no sense checking the object for null inside the [].filter(). When using TypeScript, it's a static check for arr. If the assumption is broken, then an error is thrown, which it's something I usually desire. I don't hide runtime errors. If there's a runtime error here, I'll review the assumption. Yet I'm not sure it's the case here.

share|improve this answer

edited Mar 9 at 12:30

answered Mar 9 at 3:01

André WerlangAndré Werlang

4,1622141

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Remember to check for null arr.filter(x => x ? Object.keys(x).length > 0 : false).length;
  
  – Thilina Hasantha
  Mar 9 at 3:19
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the reply and sorry, I've updated the OP again! Hopefully now I've articulated myself properly
  
  – A7DC
  Mar 9 at 3:23
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @A7DC the edit doesn't change the answer, it still complies, I guess the .length access made you think it would accumulate properties?
  
  – André Werlang
  Mar 9 at 12:16
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @ThilinaHasantha it's a valid assumption to expect the input array contains only non-null objects. Besides, it can be also desired it throws an error if that assumption fails
  
  – André Werlang
  Mar 9 at 12:19
  

  
  
  
  

add a comment | 

1

If you do:

arr.map(x=> Object.keys(x).length)

you'll get:

[ 0, 0, 0, 1 ]

If the object is empty then there are no keys and so its length is 0.

If you need a true/false result do:

arr.map(x=> Object.keys(x).length).some(x=>x>0)

Examples:

console.log("[,]", [,].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,a: 1]", [,a: 1].map(x=> Object.keys(x).length).some(x=>x>0))

share|improve this answer

edited Mar 9 at 2:33

answered Mar 9 at 2:28

R. SchifiniR. Schifini

6,84821928

add a comment | 

Your Answer

StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f55073388%2fhow-to-find-if-object-inside-array-is-not-empty%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

1

arr.filter(x => Object.keys(x).length).length

As explained in other answers, Object.keys() returns property names from a given object. The inner .length is a shortcut to filter only items that have at least one property. The outer .length tells how many objects fit the description.

UPDATE:

The [].filter() method takes a function that returns a thruthy/falsy value. A number greater than 0 is thruthy, so it's the same as .length !== 0.

The assumption here is that any element contained in the array is non-null. Under this assumption it makes no sense checking the object for null inside the [].filter(). When using TypeScript, it's a static check for arr. If the assumption is broken, then an error is thrown, which it's something I usually desire. I don't hide runtime errors. If there's a runtime error here, I'll review the assumption. Yet I'm not sure it's the case here.

share|improve this answer

edited Mar 9 at 12:30

answered Mar 9 at 3:01

André WerlangAndré Werlang

4,1622141

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Remember to check for null arr.filter(x => x ? Object.keys(x).length > 0 : false).length;
  
  – Thilina Hasantha
  Mar 9 at 3:19
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the reply and sorry, I've updated the OP again! Hopefully now I've articulated myself properly
  
  – A7DC
  Mar 9 at 3:23
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @A7DC the edit doesn't change the answer, it still complies, I guess the .length access made you think it would accumulate properties?
  
  – André Werlang
  Mar 9 at 12:16
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @ThilinaHasantha it's a valid assumption to expect the input array contains only non-null objects. Besides, it can be also desired it throws an error if that assumption fails
  
  – André Werlang
  Mar 9 at 12:19
  

  
  
  
  

add a comment | 

1

arr.filter(x => Object.keys(x).length).length

As explained in other answers, Object.keys() returns property names from a given object. The inner .length is a shortcut to filter only items that have at least one property. The outer .length tells how many objects fit the description.

UPDATE:

The [].filter() method takes a function that returns a thruthy/falsy value. A number greater than 0 is thruthy, so it's the same as .length !== 0.

The assumption here is that any element contained in the array is non-null. Under this assumption it makes no sense checking the object for null inside the [].filter(). When using TypeScript, it's a static check for arr. If the assumption is broken, then an error is thrown, which it's something I usually desire. I don't hide runtime errors. If there's a runtime error here, I'll review the assumption. Yet I'm not sure it's the case here.

share|improve this answer

edited Mar 9 at 12:30

answered Mar 9 at 3:01

André WerlangAndré Werlang

4,1622141

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Remember to check for null arr.filter(x => x ? Object.keys(x).length > 0 : false).length;
  
  – Thilina Hasantha
  Mar 9 at 3:19
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the reply and sorry, I've updated the OP again! Hopefully now I've articulated myself properly
  
  – A7DC
  Mar 9 at 3:23
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @A7DC the edit doesn't change the answer, it still complies, I guess the .length access made you think it would accumulate properties?
  
  – André Werlang
  Mar 9 at 12:16
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @ThilinaHasantha it's a valid assumption to expect the input array contains only non-null objects. Besides, it can be also desired it throws an error if that assumption fails
  
  – André Werlang
  Mar 9 at 12:19
  

  
  
  
  

add a comment | 

arr.filter(x => Object.keys(x).length).length

As explained in other answers, Object.keys() returns property names from a given object. The inner .length is a shortcut to filter only items that have at least one property. The outer .length tells how many objects fit the description.

UPDATE:

The [].filter() method takes a function that returns a thruthy/falsy value. A number greater than 0 is thruthy, so it's the same as .length !== 0.

The assumption here is that any element contained in the array is non-null. Under this assumption it makes no sense checking the object for null inside the [].filter(). When using TypeScript, it's a static check for arr. If the assumption is broken, then an error is thrown, which it's something I usually desire. I don't hide runtime errors. If there's a runtime error here, I'll review the assumption. Yet I'm not sure it's the case here.

share|improve this answer

edited Mar 9 at 12:30

answered Mar 9 at 3:01

André WerlangAndré Werlang

4,1622141

arr.filter(x => Object.keys(x).length).length

share|improve this answer

edited Mar 9 at 12:30

answered Mar 9 at 3:01

André WerlangAndré Werlang

4,1622141

answered Mar 9 at 3:01

André WerlangAndré Werlang

4,1622141

answered Mar 9 at 3:01

André WerlangAndré Werlang

4,1622141

1

If you do:

arr.map(x=> Object.keys(x).length)

you'll get:

[ 0, 0, 0, 1 ]

If the object is empty then there are no keys and so its length is 0.

If you need a true/false result do:

arr.map(x=> Object.keys(x).length).some(x=>x>0)

Examples:

console.log("[,]", [,].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,a: 1]", [,a: 1].map(x=> Object.keys(x).length).some(x=>x>0))

share|improve this answer

edited Mar 9 at 2:33

answered Mar 9 at 2:28

R. SchifiniR. Schifini

6,84821928

add a comment | 

1

If you do:

arr.map(x=> Object.keys(x).length)

you'll get:

[ 0, 0, 0, 1 ]

If the object is empty then there are no keys and so its length is 0.

If you need a true/false result do:

arr.map(x=> Object.keys(x).length).some(x=>x>0)

Examples:

console.log("[,]", [,].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,a: 1]", [,a: 1].map(x=> Object.keys(x).length).some(x=>x>0))

share|improve this answer

edited Mar 9 at 2:33

answered Mar 9 at 2:28

R. SchifiniR. Schifini

6,84821928

add a comment | 

If you do:

arr.map(x=> Object.keys(x).length)

you'll get:

[ 0, 0, 0, 1 ]

If the object is empty then there are no keys and so its length is 0.

If you need a true/false result do:

arr.map(x=> Object.keys(x).length).some(x=>x>0)

Examples:

console.log("[,]", [,].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,a: 1]", [,a: 1].map(x=> Object.keys(x).length).some(x=>x>0))

share|improve this answer

edited Mar 9 at 2:33

answered Mar 9 at 2:28

R. SchifiniR. Schifini

6,84821928

arr.map(x=> Object.keys(x).length)

[ 0, 0, 0, 1 ]

arr.map(x=> Object.keys(x).length).some(x=>x>0)

console.log("[,]", [,].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,a: 1]", [,a: 1].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,]", [,].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,a: 1]", [,a: 1].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,]", [,].map(x=> Object.keys(x).length).some(x=>x>0))

console.log("[,a: 1]", [,a: 1].map(x=> Object.keys(x).length).some(x=>x>0))

share|improve this answer

edited Mar 9 at 2:33

answered Mar 9 at 2:28

R. SchifiniR. Schifini

6,84821928

answered Mar 9 at 2:28

R. SchifiniR. Schifini

6,84821928

answered Mar 9 at 2:28

R. SchifiniR. Schifini

6,84821928