JavaScript Dynamically remove numbered array elements

Question

I have an object which looks like below

{
  "containers": [
    {
    "fields": [
        {},
        {},
        'associative1': {},
        'associative2': {}
      ] 
    }
  ]
}

So basically "fields" is an array which has elements like both fields[0], fields[1] & fields[associative1], fields[associative2]

My question is can I dynamically remove "just" the numbered elements... so finally 'fields' should just have associative1, associative2 elements

That array is not valid, you can't have named elements in an array literal. — Barmar
– Barmar, Commented Oct 14, 2017 at 6:39
Where and how you get this object, seems like it is not actually data. — GRESPL Nagpur
– GRESPL Nagpur, Commented Oct 14, 2017 at 7:03

joshp · Accepted Answer · 2017-10-14 07:23:55Z

1

Creating a valid object that looks like what it seems you intend...

var a = [{abc:1},{xyz:2}];
a.associative1 = {};
a.associative2 = {};
console.log(a);

Output (from Chrome)

(2) [{…}, {…}, associative1: {…}, associative2: {…}]
0: {abc: 1}
1: {xyz: 2}
associative1: {}
associative2: {}
length: 2

You can remove just the numbered array elements like this...

a.splice(0,a.length);

Or if the Array object is contained in a larger object something like this will work...

c.containers[0].fields.splice(0,c.containers[0].fields.length)

answered Oct 14, 2017 at 7:23

joshp

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4 Comments

copenndthagen Over a year ago

Looks awesome...Just a quick question....What exactly is the type of "a" here & how does JavaScript allow assigning a.associative1 if It is declared as an array ...like it seems to be mixing types

joshp Over a year ago

@testndtv Javascript reports typeof a === 'object'. Arrays in Javascript have type 'object'. But, not every object in Javascript is an array. Array.isArray(a) === true. But Array.isArray({0:"hi"})===false. So you may want to check whether an object is an array before attempting to use Array methods like splice, that do not exist for non-Array objects.

joshp Over a year ago

@testndtv Recommend developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… The Description section speaks briefly about Javascript objects' associative array properties vs. Array elements.

copenndthagen Over a year ago

Thx...Yes, I do see on the page why/how that syntax is allowed...But still wondering what "object property collection" of an array means (as referred on developer.mozilla.org/en-US/docs/Web/JavaScript/…)

Shiladitya · Accepted Answer · 2017-10-14 07:26:31Z

1

Here you go with a solution

var data = {
  "containers": [
    {
    "fields": [
        {'abc': 1},
        {'xyz': 2},
        {'associative1': {}},
        {'associative2': {}}
    ]   
    }
  ]
};


for(var k in data["containers"][0]["fields"]){
 for(var key in data["containers"][0]["fields"][k]){
  if(!isNaN(data["containers"][0]["fields"][k][key])){
    delete data["containers"][0]["fields"][k];
  }
 }
}

data["containers"][0]["fields"] = data["containers"][0]["fields"].filter(function( element ) {
   return element !== undefined;
});

console.log(data);

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

Your JSON is invalid. I've changed the JSON a little bit.

Hope this will help you.

answered Oct 14, 2017 at 7:26

Shiladitya

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1 Comment

Shiladitya Over a year ago

@testndtv If you are satisfied please accept the answer.

doublejosh · Accepted Answer · 2017-10-14 17:01:08Z

0

It's an invalid object. The fields array include name properties, which is not allowed. Fields must be an object in that case. If test setting a variable to that object (just in a browser console) it will fail.

edited Oct 14, 2017 at 17:01

doublejosh

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answered Oct 14, 2017 at 6:50

parth494

1

1 Comment

copenndthagen Over a year ago

So I can reference fields[0], fields[1], fields[associative1], etc

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