How do I count the number of objects a specific value from mutliple nested objects?

Question

var foodwebsites = {
  "bacon": [{
    "url": "stackoverflow.com",
  }],
  "icecream": [{
    "url": "example.com",
  }],
  "cheese": [{
    "url": "example.com",
  }]
}

var baconfoodwebsites = foodwebsites.bacon.filter(function(elem) {
  return elem.url == 'example.com';
}).length;

var icecreamfoodwebsites = foodwebsites.icecream.filter(function(elem) {
  return elem.url == 'example.com';
}).length;

var cheesefoodwebsites = foodwebsites.cheese.filter(function(elem) {
  return elem.url == 'example.com';
}).length;

var allfoodwebsites = baconfoodwebsites + icecreamfoodwebsites + cheesefoodwebsites;

console.log(baconfoodwebsites, icecreamfoodwebsites, cheesefoodwebsites, allfoodwebsites)

I'd like to do the exact same thing without the repetion of all these individual nested objects (bacon, icecream and cheese).

I assume the answer would be like:

var allfoodwebsites = foodwebsites=.filter(function( elem) {
    return elem.url == 'example.com';
}).length;

Additional Info:

I'd like to use only jQuery + Pure Javascript if possible.

I'd like to find all nested objects with "url": "example.com"

There was no JSON here. You have POJOs - Plain Old JavaScript Objects — mplungjan
– mplungjan, Commented Apr 11, 2019 at 21:28
Don't use a filter for counting. You're creating an unnecessary array in memory. — Ele
– Ele, Commented Apr 11, 2019 at 21:30
Please clarify with the expected output, what you need to count? All available URLs? The number of URLs matching some pattern? — Shidersz
– Shidersz, Commented Apr 11, 2019 at 21:35

charlietfl · Accepted Answer · 2019-04-11 21:42:36Z

2

Using Object.values, Array#reduce() & Array#flat() . Note flat() may need polyfill in some environments

let foodwebsites = {"bacon": [{"url": "stackoverflow.com",}],"icecream": [{"url": "example.com",}],"cheese": [{"url": "example.com",}]};


const  getUrlCount = (url) => {
   return Object.values(foodwebsites)
       .flat()
       .reduce((a, {url:u})=> a + (url === u) , 0)

}

console.log(getUrlCount("example.com"))

edited Apr 11, 2019 at 21:42

answered Apr 11, 2019 at 21:40

charlietfl

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2 Comments

Jonas Wilms Over a year ago

++a ? why not just a + 1 ? Or even a + (url === u) ?

charlietfl Over a year ago

@JonasWilms never been conditioned to use booleans like that. Simple shortcut

Ele · Accepted Answer · 2019-04-11 21:36:34Z

2

The best option is the function reduce for counting approaches.

let foodwebsites = {"bacon": [{"url": "stackoverflow.com",}],"icecream": [{"url": "example.com",}],"cheese": [{"url": "example.com",}]};
let allfoodwebsites = Object.values(foodwebsites).
          reduce((a, array) => a + array.
            reduce((a, {url}) => a + (url === "example.com"), 0), 0);

console.log(allfoodwebsites);

edited Apr 11, 2019 at 21:36

answered Apr 11, 2019 at 21:35

Ele

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Comments

zfrisch · Accepted Answer · 2019-04-11 21:45:31Z

1

Solution:

You can create a function that will iterate the object keys and search for a property and value inside each accessed key's array of child objects:

let amount = (p, v, i = 0) => 
(Object.keys(foodwebsites).forEach(k => foodwebsites[k].forEach(o => o[p] === v && i++))
, i);

and it can be used like this:

amount("url", "example.com"); // 2

Working Code Snippet:

var foodwebsites = {
  "bacon": [{
    "url": "stackoverflow.com",
  }],
  "icecream": [{
    "url": "example.com",
  }],
  "cheese": [{
    "url": "example.com",
  }]
}

    let amount = (p, v, i = 0) => 
    (Object.keys(foodwebsites).forEach(k => foodwebsites[k].forEach(o => o[p] === v && i++))
    , i);

console.log(
  amount("url", "example.com")
);
//2

edited Apr 11, 2019 at 21:45

answered Apr 11, 2019 at 21:39

zfrisch

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2 Comments

Tigerrrrr Over a year ago

So would it be let amount = amount("url", "example.com"); ?

zfrisch Over a year ago

@Tigerrrrr yes.

Jonas Wilms · Accepted Answer · 2019-04-12 07:01:54Z

1

I'd actually built one array of all these nested entries:

  const sites = Object.values(foodwebsites).flat();

Then you can easily iterate over it and count all the keys:

 const count = (arr, key, value) => arr.reduce((acc, it) => acc + it[key] === value, 0);

 console.log(
   count(sites, "url", "example.com"),
   count(sites, "url", "stackoverflow.com")
 );

edited Apr 12, 2019 at 7:01

answered Apr 11, 2019 at 21:44

Jonas Wilms

139k20 gold badges164 silver badges164 bronze badges

3 Comments

Jonas Wilms Over a year ago

@mplungjan on mobile.

Jonas Wilms Over a year ago

@mplungjan you are right with the typo, but surely I can

mplungjan Over a year ago

My bad . Missed that the second time

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