Removing numerous key/value pairs from an object in real-time

Question

Removing numerous key/value pairs from an object in real-time

Suppose I have an array of objects and I want to exclude certain keys/values. Instead of using the traditional delete method to remove one key/value pair, is there a way to specify which pairs I want to keep and remove all others? For example, in this array of objects, I only wish to retain trackName, kind, and price:

var tracks = [{
    trackNumber: "01",
    trackName: "Track 1",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "02",
    trackName: "Track 2",
    trackDuration: "5:15",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "03",
    trackName: "Track 3",
    trackDuration: "5:07",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "04",
    trackName: "Track 4",
    trackDuration: "0:16",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "05",
    trackName: "Track 5",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}];

javascript arrays json object key-value

Answer 1

Answer №1

Loop through the array and select specific properties from each object.

let properties = ['name', 'type', 'cost'];

for(let j = 0; j < itemsArray.length; j++){

    for(let prop in itemsArray[j]){
        if(properties.indexOf(prop) === -1) delete itemsArray[j][prop];
    }

}

Answer 2

Loop through the array and select specific properties from each object.

let properties = ['name', 'type', 'cost'];

for(let j = 0; j < itemsArray.length; j++){

    for(let prop in itemsArray[j]){
        if(properties.indexOf(prop) === -1) delete itemsArray[j][prop];
    }

}

Answer 3

Answer №2

My recommendation for a more refined solution would be:

// Transform the existing array of objects into a new array
var updatedTracks = jQuery.map(tracks, function(item, position){
    return {"trackName": item.trackName, "type": item.type, "cost": item.cost};
}); 
// Clear the original array   
tracks = null;

Answer 4

My recommendation for a more refined solution would be:

// Transform the existing array of objects into a new array
var updatedTracks = jQuery.map(tracks, function(item, position){
    return {"trackName": item.trackName, "type": item.type, "cost": item.cost};
}); 
// Clear the original array   
tracks = null;

Answer 5

Answer №3

Would you be okay with utilizing the underscore method ".pick(object, *keys) " and ".omit(object, *keys) " to extract specific keys from an object and then adding the resulting objects into a new array?

Answer 6

Would you be okay with utilizing the underscore method ".pick(object, *keys) " and ".omit(object, *keys) " to extract specific keys from an object and then adding the resulting objects into a new array?

Answer 7

Answer №4

An effective approach:

// specify the data you wish to retain:
var dataToRetain = ['trackName', 'kind', 'price'];

// iterate through each main element of tracks:
for (var index=0; index<tracks.length; index++)
    // loop through each property of the current track:
    for (var prop in tracks[index])
        // check if the current track property is in the list of desired data:
        if (dataToRetain.indexOf(prop) < 0)
            delete tracks[index][prop];

Answer 8

An effective approach:

// specify the data you wish to retain:
var dataToRetain = ['trackName', 'kind', 'price'];

// iterate through each main element of tracks:
for (var index=0; index<tracks.length; index++)
    // loop through each property of the current track:
    for (var prop in tracks[index])
        // check if the current track property is in the list of desired data:
        if (dataToRetain.indexOf(prop) < 0)
            delete tracks[index][prop];

Answer 9

Answer №5

Here is a straightforward solution that I came up with:

/**
 * Create a new collection containing only specified properties
 * @param {Array} the original collection of items
 * @param {Array} properties to be retained
 */

function keepCollectionProperties(collection, properties) {
    return collection.map(function(item) {
        var newItem = {}
        for(var i = 0, prop; prop = properties[i]; i++)
            if (typeof item[prop] !== 'undefined')
                newItem[prop] = item[prop]
        return newItem
    })
}

var tracks = [{
    trackNumber: "01",
    trackName: "Track 1",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "02",
    trackName: "Track 2",
    trackDuration: "5:15",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "03",
    trackName: "Track 3",
    trackDuration: "5:07",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "04",
    trackName: "Track 4",
    trackDuration: "0:16",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "05",
    trackName: "Track 5",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}];

var output = keepCollectionProperties(tracks, ['trackName', 'kind', 'price'])
document.write(JSON.stringify(output))

Important: avoid using delete as it alters the object's structure and can impact performance. Try setting unwanted properties to null like item.prop = null. This function creates a new collection, so it may not be necessary, but if you intend to repopulate the new collection again, setting unwanted props to null would be recommended.

Answer 10

Here is a straightforward solution that I came up with:

/**
 * Create a new collection containing only specified properties
 * @param {Array} the original collection of items
 * @param {Array} properties to be retained
 */

function keepCollectionProperties(collection, properties) {
    return collection.map(function(item) {
        var newItem = {}
        for(var i = 0, prop; prop = properties[i]; i++)
            if (typeof item[prop] !== 'undefined')
                newItem[prop] = item[prop]
        return newItem
    })
}

var tracks = [{
    trackNumber: "01",
    trackName: "Track 1",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "02",
    trackName: "Track 2",
    trackDuration: "5:15",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "03",
    trackName: "Track 3",
    trackDuration: "5:07",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "04",
    trackName: "Track 4",
    trackDuration: "0:16",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "05",
    trackName: "Track 5",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}];

var output = keepCollectionProperties(tracks, ['trackName', 'kind', 'price'])
document.write(JSON.stringify(output))

Important: avoid using delete as it alters the object's structure and can impact performance. Try setting unwanted properties to null like item.prop = null. This function creates a new collection, so it may not be necessary, but if you intend to repopulate the new collection again, setting unwanted props to null would be recommended.

Answer 11

Answer №6

Uncertain if this meets your requirements, but it will iterate through a list and return a new list containing only the specified keys. The keys are provided in an Array.

function ExtractKeys(keys, list){
    var outputArr = [];
    for (var i in list){
       var row = {};
       for (key in list[i]){
          row[key] = list[i][key];
       }
       outputArr.push(row);
    }
    return outputArr;
}

There are alternate ways to modify the original list as well, although I opted to create a new list based on my understanding of your intentions.

If modifying the original list is desired, you could consider:

var select = ["a","b"]
list.map(function(val,index, array)
   {
   var keys = Object.keys(val);
   for (var key in keys){
      if(-1 == select.indexOf(keys[key]])  delete val[keys[key]];
   }}.bind(this));

I believe this approach should achieve the desired outcome by filtering out keys not included in the 'select' array from the original list.

Answer 12

Uncertain if this meets your requirements, but it will iterate through a list and return a new list containing only the specified keys. The keys are provided in an Array.

function ExtractKeys(keys, list){
    var outputArr = [];
    for (var i in list){
       var row = {};
       for (key in list[i]){
          row[key] = list[i][key];
       }
       outputArr.push(row);
    }
    return outputArr;
}

There are alternate ways to modify the original list as well, although I opted to create a new list based on my understanding of your intentions.

If modifying the original list is desired, you could consider:

var select = ["a","b"]
list.map(function(val,index, array)
   {
   var keys = Object.keys(val);
   for (var key in keys){
      if(-1 == select.indexOf(keys[key]])  delete val[keys[key]];
   }}.bind(this));

I believe this approach should achieve the desired outcome by filtering out keys not included in the 'select' array from the original list.

Removing numerous key/value pairs from an object in real-time

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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