CODEWITHSUNDEEP
javascriptarrays
Donald Duck is with Ukraine
Donald Duck is with Ukraine

Reputation: 8902

Count the number of times a same value appears in a javascript array

I would like to know if there is a native javascript code that does the same thing as this:

function f(array,value){
    var n = 0;
    for(i = 0; i < array.length; i++){
        if(array[i] == value){n++}
    }
    return n;
}

Upvotes: 57

Views: 165249

Answers (12)

Edgy
Edgy

Reputation: 491

Another option is to use Array.filter():

count = myArray.filter(x => x === searchValue).length;

Upvotes: 49

Mr.com
Mr.com

Reputation: 1

var obj = [];
var array = ['a', 'a', 'a', 'b', 'c', 'c', 'd', 'd', 'd', 'd', 'd', 'd'];

array.forEach(element => {
  let count = 1;
  array.forEach(loopo => {
    if(element == loopo)
     {
       obj[loopo] = count++;
     }
  })
});
console.log(obj);

Upvotes: -1

RomanPerekhrest
RomanPerekhrest

Reputation: 92894

There might be different approaches for such purpose.
And your approach with for loop is obviously not misplaced(except that it looks redundantly by amount of code).
Here are some additional approaches to get the occurrence of a certain value in array:

  • Using Array.forEach method:

      var arr = [2, 3, 1, 3, 4, 5, 3, 1];

  function getOccurrence(array, value) {
      var count = 0;
      array.forEach((v) => (v === value && count++));
      return count;
  }

  console.log(getOccurrence(arr, 1));  // 2
  console.log(getOccurrence(arr, 3));  // 3

  • Using Array.filter method:

      function getOccurrence(array, value) {
      return array.filter((v) => (v === value)).length;
  }

  console.log(getOccurrence(arr, 1));  // 2
  console.log(getOccurrence(arr, 3));  // 3

Upvotes: 84

Sandra
Sandra

Reputation: 11

This is how I did mine using just a for loop. It's not as sophisticated as some of the answers above but it worked for me.

function getNumOfTimes(arrayOfNums){
    let found = {}
        for (let i = 0; i < arrayOfNums.length; i++) {
            let keys = arrayOfNums[i].toString()
            found[keys] = ++found[arrayOfNums[i]] || 1
        }

    return found
}

getNumOfTimes([1, 4, 4, 4, 5, 3, 3, 3])

// { '1': 1, '3': 3, '4': 3, '5': 1 }

Upvotes: 1

David Ouma
David Ouma

Reputation: 41

You could use the Array filter method and find the length of the new array like this

const count = (arr, value) => arr.filter(val => val === value).length

Upvotes: 3

Panda
Panda

Reputation: 1

let countValue = 0;

Array.forEach((word) => {
  if (word === searchValue) {
    return countValue ++;
  }
});
console.log(`The number of word 'asdf': ${countValue}`);

I used this code to count the number of a given word in a text which was previously converted into an array.

Upvotes: 0

Steve.g
Steve.g

Reputation: 498

const arr = ["a", "a", "a", "b", "b", "b", "b", "c", "c", "c"];
let count = 0;

function countValues(array, countItem) {
  array.forEach(itm => {
    if (itm == countItem) count++;
  });
  console.log(`${countItem} ${count}`);
}
countValues(arr, "c");

Upvotes: 2

Jaint Rai
Jaint Rai

Reputation: 21

let ar = [2,2,3,1,4,9,5,2,1,3,4,4,8,5];

const countSameNumber = (ar: any, findNumber: any) => {
    let count = 0;
    ar.map((value: any) => {
        if(value === findNumber) {
            count = count + 1;
        }
    })
    return count;
}


let set = new Set(ar);
for (let entry of set) {
    console.log(entry+":", countSameNumber(ar, entry));
}

Upvotes: 2

Maira Diaz Marraffini
Maira Diaz Marraffini

Reputation: 169

Here is my solution without using an additional object and using reduce:

const occurrencesOf = (number,numbers) => numbers.reduce((counter, currentNumber)=> (number === currentNumber ? counter+1 : counter),0);
occurrencesOf(1, [1,2,3,4,5,1,1]) // returns 3
occurrencesOf(6, [1,2,3,4,5,1,1]) // returns 0
occurrencesOf(5, [1,2,3,4,5,1,1]) // returns 1

Upvotes: 9

JJ Cha
JJ Cha

Reputation: 99

You can also use forEach

let countObj = {};
let arr = [1,2,3,1,2,3,4];

let countFunc = keys => {
  countObj[keys] = ++countObj[keys] || 1;
}

arr.forEach(countFunc);

// {1: 2, 2: 2, 3: 2, 4: 1}

Upvotes: 9

Saeed D.
Saeed D.

Reputation: 1176

You may want to use indexOf() function to find and count each value in array

function g(array,value){
  var n = -1;
  var i = -1;
  do {
    n++;
    i = array.indexOf(value, i+1);
  } while (i >= 0  );

  return n;
}

Upvotes: 0

omarjmh
omarjmh

Reputation: 13896

You could use reduce to get there:

Working example

var a = [1,2,3,1,2,3,4];

var map = a.reduce(function(obj, b) {
  obj[b] = ++obj[b] || 1;
  return obj;
}, {});

Upvotes: 32

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