How to find the length of a JSON object [duplicate]

Question

 var legend=[{"min":0,
            "max":first_color,
            "color":"#1a9850"
  },
  {
      "min":first_color,
      "max":sec_color,
      "color":"#fee08b"
  },
  {
      "min":sec_color,
      "max":thrd_color,
      "color":"#ff3300"
  },
  {
      "min":thrd_color,
      "max":frth_color,
      "color":"#d73027"
      "Abc":"gsfg"
  }

  ];

I'd like to find out each object's property count. E.g. the first 3 objects have 3 properties and 4th one has 4 props, etc.

1. Iterate 2. Get current element in array 3. Object.keys(arrayEl).length — Tushar
– Tushar, Commented Nov 16, 2016 at 6:07
Where are you stuck? Are you having a problem looping over the elements/objects in the array? Are you having a problem getting the list of each object's keys? — user663031
– user663031, Commented Nov 16, 2016 at 6:11

Pranav C Balan · Accepted Answer · 2016-11-16 06:09:13Z

11

Iterate over the array and get object property names count.

var legend = [{
  "min": 0,
  "max": 'first_color',
  "color": "#1a9850"
}, {
  "min": 'first_color',
  "max": 'sec_color',
  "color": "#fee08b"
}, {
  "min": 'sec_color',
  "max": 'thrd_color',
  "color": "#ff3300"
}, {
  "min": 'thrd_color',
  "max": 'frth_color',
  "color": "#d73027",
  "Abc": "gsfg"
}];

var res = legend.map(function(v) {
  console.log(Object.keys(v).length);
  return Object.keys(v).length;
});

console.log(res);

answered Nov 16, 2016 at 6:09

Pranav C Balan

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6 Comments

Brian Over a year ago

I really must remember to use map more +1 for a nice clean solution!

Gaurav Singh Over a year ago

one more silly question what if i want to know which field are persent in json array in first there are min max and color and in fourth one min max color and Abc etc

Gaurav Singh Over a year ago

coz for iterating object we must know key

Brian Over a year ago

Object.keys returns an array of keys so you can iterate over that using either map again or a regular for loop.

Gaurav Singh Over a year ago

thx you so much..............

|

Community · Accepted Answer · 2017-05-23 10:33:01Z

7

'JSON' object is the wrong terminology.
Referring to 'Length of a JavaScript object', the best solution would be:

Object.keys(obj).length

But a better solution would be to prototype Object

Object.size = function(obj) {
   return Object.keys(obj).length;
}

edited May 23, 2017 at 10:33

CommunityBot

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answered Nov 16, 2016 at 6:09

Amit

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2 Comments

user663031 Over a year ago

Why is that a better solution?

Amit Over a year ago

@torazaburo Because it would be cleaner for more than 1 usage. Object.size(obj) is simpler and more human readable.

Deep · Accepted Answer · 2016-11-16 06:10:11Z

4

you can use Object.keys

 console.log(Object.keys(legend[0]).length)// 3

 console.log(Object.keys(legend[3]).length);//4

answered Nov 16, 2016 at 6:10

Deep

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