Creating an array dynamically by parsing a JSON object in Javascript

Question

Creating an array dynamically by parsing a JSON object in Javascript

I am currently working with a JSON object that looks like this:

var testJSON = [
    { "AssetA": "asset_a", "AssetB": "asset_b" },
    { "AssetA": "asset_a", "AssetB": "asset_b" },
    { "AssetA": "asset_c", "AssetB": "asset_d" },
{ "AssetA": "asset_c", "AssetB": "asset_e" }];

My objective is to iterate through the object and add duplicate keys to a new array called usedAssets. I have written some code to achieve this:

var usedAssets = [];

for (var key in testJSON) {
    console.log("Current key: " + key + " " + "value: : " +  testJSON[key].AssetA);
    console.log("Current key: " + key + " " + "value: : " + testJSON[key].AssetB);

    // check if in array
    if ((isInArray(testJSON[key].AssetA, usedAssets) || isInArray(testJSON[key].AssetB, usedAssets))) {
        break;
    }
    else {
        usedAssets.push(testJSON[key].AssetA);
        usedAssets.push(testJSON[key].AssetB);
    }
}
console.log(usedAssets);



function isInArray(value, array) {
    return array.indexOf(value) > -1;
}

However, the output I get is an array with only asset_a and asset_b. The usedAssets array should actually contain asset_a, asset_b, and asset_c. Ultimately, my goal is to determine at the end of the loop how many times each unique asset was used.

javascript json

Answer 1

Answer №1

To find the occurrence of each element in an array and each property in an object, you can iterate through both and keep a count.

var testJSON = [{ "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_c", "AssetB": "asset_d" }, { "AssetA": "asset_c", "AssetB": "asset_e" }],
    count = {};

testJSON.forEach(o => Object.keys(o).forEach(k => count[o[k]] = (count[o[k]] || 0) + 1));

console.log(count);
console.log(Object.keys(count).filter(k => count[k] > 1));

.as-console-wrapper { max-height: 100% !important; top: 0; }

ES5

var testJSON = [{ "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_c", "AssetB": "asset_d" }, { "AssetA": "asset_c", "AssetB": "asset_e" }],
    count = {};

testJSON.forEach(function (o) {
    Object.keys(o).forEach(function (k) {
        count[o[k]] = (count[o[k]] || 0) + 1;
    });
});

console.log(count);
console.log(Object.keys(count).filter(function (k) {
    return count[k] > 1;
}));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

To find the occurrence of each element in an array and each property in an object, you can iterate through both and keep a count.

var testJSON = [{ "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_c", "AssetB": "asset_d" }, { "AssetA": "asset_c", "AssetB": "asset_e" }],
    count = {};

testJSON.forEach(o => Object.keys(o).forEach(k => count[o[k]] = (count[o[k]] || 0) + 1));

console.log(count);
console.log(Object.keys(count).filter(k => count[k] > 1));

.as-console-wrapper { max-height: 100% !important; top: 0; }

ES5

var testJSON = [{ "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_a", "AssetB": "asset_b" }, { "AssetA": "asset_c", "AssetB": "asset_d" }, { "AssetA": "asset_c", "AssetB": "asset_e" }],
    count = {};

testJSON.forEach(function (o) {
    Object.keys(o).forEach(function (k) {
        count[o[k]] = (count[o[k]] || 0) + 1;
    });
});

console.log(count);
console.log(Object.keys(count).filter(function (k) {
    return count[k] > 1;
}));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

Answer №2

This code snippet showcases a method to extract unique values from an array by reducing it to only the values that have been seen.

    var exampleArray = [
        { "ItemA": "item_a", "ItemB": "item_b" },
        { "ItemA": "item_a", "ItemB": "item_b" },
        { "ItemA": "item_c", "ItemB": "item_d" },
    { "ItemA": "item_c", "ItemB": "item_e" }];

    var seenValues = {};
    var uniqueValues = exampleArray.map(function(data){
      return Object.keys(data).map(function(key){
        return data[key];
      })
    }).reduce(function(prev, current) {
      return prev.concat(current);
    }, []).filter(function(item){
      if (!seenValues[item]){
          seenValues[item] = 1;
          return true;
      }
      seenValues[item] += 1;
      return false;
    })

    console.log('Seen Values: ' + JSON.stringify(seenValues));
    console.log('Unique Values: ' + uniqueValues);

Answer 4

This code snippet showcases a method to extract unique values from an array by reducing it to only the values that have been seen.

    var exampleArray = [
        { "ItemA": "item_a", "ItemB": "item_b" },
        { "ItemA": "item_a", "ItemB": "item_b" },
        { "ItemA": "item_c", "ItemB": "item_d" },
    { "ItemA": "item_c", "ItemB": "item_e" }];

    var seenValues = {};
    var uniqueValues = exampleArray.map(function(data){
      return Object.keys(data).map(function(key){
        return data[key];
      })
    }).reduce(function(prev, current) {
      return prev.concat(current);
    }, []).filter(function(item){
      if (!seenValues[item]){
          seenValues[item] = 1;
          return true;
      }
      seenValues[item] += 1;
      return false;
    })

    console.log('Seen Values: ' + JSON.stringify(seenValues));
    console.log('Unique Values: ' + uniqueValues);

Answer 5

Answer №3

It appears that you are attempting to tally how many times each asset was utilized... One straightforward approach is to maintain a map of previously seen objects. Using Array.prototype.reduce can help with this.

var testJSON = [{"AssetA":"asset_a","AssetB":"asset_b"},{"AssetA":"asset_a","AssetB":"asset_b"},{"AssetA":"asset_c","AssetB":"asset_d"},{"AssetA":"asset_c","AssetB":"asset_e"}];

var usage = testJSON.reduce((prev, next) => {
  prev[next.AssetA] = next.AssetA in prev ? prev[next.AssetA] + 1 : 1;
  prev[next.AssetB] = next.AssetB in prev ? prev[next.AssetB] + 1 : 1;
  return prev;
}, {});
console.log('How much were they used?', usage);
// If you want to know which ones were used two or more times, you can use
console.log('Used more than once', Object.keys(usage).filter(key => usage[key] > 1))

An alternative way without using reduce would be as follows:

var usage = {};
testJSON.forEach(el => {
    usage[el.AssetA] = el.AssetA in usage ? usage[el.AssetA] + 1 : 1;
    usage[el.AssetB] = el.AssetB in usage ? usage[el.AssetB] + 1 : 1;
});
console.log('How much were they used?', usage);
// If you want to know which ones were used two or more times, you can use
console.log('Used more than once', Object.keys(usage).filter(key => usage[key] > 1))

Answer 6

It appears that you are attempting to tally how many times each asset was utilized... One straightforward approach is to maintain a map of previously seen objects. Using Array.prototype.reduce can help with this.

var testJSON = [{"AssetA":"asset_a","AssetB":"asset_b"},{"AssetA":"asset_a","AssetB":"asset_b"},{"AssetA":"asset_c","AssetB":"asset_d"},{"AssetA":"asset_c","AssetB":"asset_e"}];

var usage = testJSON.reduce((prev, next) => {
  prev[next.AssetA] = next.AssetA in prev ? prev[next.AssetA] + 1 : 1;
  prev[next.AssetB] = next.AssetB in prev ? prev[next.AssetB] + 1 : 1;
  return prev;
}, {});
console.log('How much were they used?', usage);
// If you want to know which ones were used two or more times, you can use
console.log('Used more than once', Object.keys(usage).filter(key => usage[key] > 1))

An alternative way without using reduce would be as follows:

var usage = {};
testJSON.forEach(el => {
    usage[el.AssetA] = el.AssetA in usage ? usage[el.AssetA] + 1 : 1;
    usage[el.AssetB] = el.AssetB in usage ? usage[el.AssetB] + 1 : 1;
});
console.log('How much were they used?', usage);
// If you want to know which ones were used two or more times, you can use
console.log('Used more than once', Object.keys(usage).filter(key => usage[key] > 1))

Creating an array dynamically by parsing a JSON object in Javascript

Answer №1

Answer №2

Answer №3

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