Count the occurrences of values in a JSON object using JavaScript

Question

Count the occurrences of values in a JSON object using JavaScript

I'm dealing with a JSON array in vanilla JavaScript (no JQuery) and I've hit a roadblock.

My task is to identify each unique value for 'Service' and calculate the frequency of each value.

For example, if the value 100 appears 3 times and the value 101 appears 5 times, the desired result should look like:

{ "100" : "3", "101" : "5"}

I'd prefer not to resort to a traditional loop if there's a more succinct solution available such as using forEach()

javascript json

Answer 1

Answer №1

To start, you should first transform your JSON array into an object array:

let json_arr = '[200, 201, 200, 202, 201]';
let objArr = JSON.parse(json_arr);

After that, it's a matter of counting, which will vary depending on the elements in your array. If they are numbers, you can use a simple approach like this:

let counts = {};
objArr.forEach(function(item) {
    counts[item] = counts[item] ? counts[item] + 1 : 1;
});

This will give you

counts = {'200': 2, '201': 2, '202': 1}

.

Answer 2

To start, you should first transform your JSON array into an object array:

let json_arr = '[200, 201, 200, 202, 201]';
let objArr = JSON.parse(json_arr);

After that, it's a matter of counting, which will vary depending on the elements in your array. If they are numbers, you can use a simple approach like this:

let counts = {};
objArr.forEach(function(item) {
    counts[item] = counts[item] ? counts[item] + 1 : 1;
});

This will give you

counts = {'200': 2, '201': 2, '202': 1}

.

Answer 3

Answer №2

Don't feel obligated to use

<array>.forEach(<callback>)

, as an alternative you can opt for a traditional for..of loop:

let output = {};
for (let value of data) output[value] = output[value] ? output[value] + 1 : 1;

Answer 4

Don't feel obligated to use

<array>.forEach(<callback>)

, as an alternative you can opt for a traditional for..of loop:

let output = {};
for (let value of data) output[value] = output[value] ? output[value] + 1 : 1;

Count the occurrences of values in a JSON object using JavaScript

Answer №1

Answer №2

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