Creating a JSON property value in real-time

Question

Creating a JSON property value in real-time

JSON object structure:

{
    "critiquesAvg": 4.75: , 
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
}

I am seeking assistance in dynamically calculating the value of critiquesAvg by averaging the stars property from the critiques array.

EDIT: Upon further examination, I encountered a different challenge:

var dealers = [{
    "id", 1874
    "critiquesAvg": 4.75 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
},
{
    "id": 1345,
    "critiquesAvg": 5 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 5
        }
    ]
}
];

In this scenario, I require assistance in dynamically computing the values of the critiquesAvg property based on the average critiques for each dealer's data entry.

javascript arrays json dynamic

Answer 1

Answer №1

To tackle this problem, I recommend using the reduce function (view code snippet here):

var data = {
    "critiquesAvg": 4.75, 
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
};

var sum = data.critiques.reduce(function(x, y) { return x.stars + y.stars });
var average = sum / data.critiques.length;

data.critiquesAvg = average;

To address the revised question, you should incorporate an additional loop, possibly utilizing forEach (updated fiddle here):

dealers.forEach(function(data) {
    var sum = data.critiques.reduce(function(x, y) { return x.stars + y.stars });
    var average = sum / data.critiques.length;

    data.critiquesAvg = average;
});

Answer 2

To tackle this problem, I recommend using the reduce function (view code snippet here):

var data = {
    "critiquesAvg": 4.75, 
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
};

var sum = data.critiques.reduce(function(x, y) { return x.stars + y.stars });
var average = sum / data.critiques.length;

data.critiquesAvg = average;

To address the revised question, you should incorporate an additional loop, possibly utilizing forEach (updated fiddle here):

dealers.forEach(function(data) {
    var sum = data.critiques.reduce(function(x, y) { return x.stars + y.stars });
    var average = sum / data.critiques.length;

    data.critiquesAvg = average;
});

Answer 3

Answer №2

To achieve this, you can swap out critiquesAvg with a custom function:

calculateAverageRating: function(){
    var totalStars = 0;
    for(i=0;i<this.ratings.length;i++) {
        totalStars += this.ratings[i].stars;
    }
    return totalStars / this.ratings.length;
},

For more details, refer to the script.js in this Plunker: http://plnkr.co/edit/zAbCdEfGhIjKlMnPqR?s=preview

Answer 4

To achieve this, you can swap out critiquesAvg with a custom function:

calculateAverageRating: function(){
    var totalStars = 0;
    for(i=0;i<this.ratings.length;i++) {
        totalStars += this.ratings[i].stars;
    }
    return totalStars / this.ratings.length;
},

For more details, refer to the script.js in this Plunker: http://plnkr.co/edit/zAbCdEfGhIjKlMnPqR?s=preview

Answer 5

Answer №3

Ensure to add an init function to your object, where all calculations are performed. In many object-oriented languages, these calculations are typically done in the constructor. Similarly, you can achieve similar functionality with a custom method acting as a constructor to set up the initial state of your object.

var obj = ({
  "critiquesAvg": 0, 
  "critiques": [{
    'author': 'John Does',
    'comment': "I like it",
    'stars': 5
  }, {
    'author': 'Jacob Works',
    'comment': "I like it too",
    'stars': 4.5
  }],
  init: function() {
    var result = this.critiques.reduce(function(prev, current, idx, arr) {
      return prev['stars'] + current['stars'];
    });
    this.critiquesAvg = result / this.critiques.length;
    return this;
  }
}).init(); // invoking the init method inline here (coding pattern)

This coding pattern is often used to set object states, especially when using object literal syntax in JavaScript.

DEMO

Updated answer

Follows a similar pattern, but instead of having an init method for each object, a common initialize method performs the same operation.

var initialize = function() {
  var result = this.critiques.reduce(function(prev, current, idx, arr) {
    return prev['stars'] + current['stars'];
  });
  this.critiquesAvg = result / this.critiques.length;
  return this;
};

var dealers = [({
  "id": 1874,
  "critiquesAvg": 0,
  "critiques": [{
    'author': 'John Does',
    'comment': "I like it",
    'stars': 5
  }, {
    'author': 'Jacob Works',
    'comment': "I like it too",
    'stars': 4.5
  }],
  init: initialize
}).init(), ({
  "id": 1345,
  "critiquesAvg": 0,
  "critiques": [{
    'author': 'John Does',
    'comment': "I like it",
    'stars': 5
  }, {
    'author': 'Jacob Works',
    'comment': "I like it too",
    'stars': 5
  }],
  init: initialize
}).init()];

DEMO

Answer 6

Ensure to add an init function to your object, where all calculations are performed. In many object-oriented languages, these calculations are typically done in the constructor. Similarly, you can achieve similar functionality with a custom method acting as a constructor to set up the initial state of your object.

var obj = ({
  "critiquesAvg": 0, 
  "critiques": [{
    'author': 'John Does',
    'comment': "I like it",
    'stars': 5
  }, {
    'author': 'Jacob Works',
    'comment': "I like it too",
    'stars': 4.5
  }],
  init: function() {
    var result = this.critiques.reduce(function(prev, current, idx, arr) {
      return prev['stars'] + current['stars'];
    });
    this.critiquesAvg = result / this.critiques.length;
    return this;
  }
}).init(); // invoking the init method inline here (coding pattern)

This coding pattern is often used to set object states, especially when using object literal syntax in JavaScript.

DEMO

Updated answer

Follows a similar pattern, but instead of having an init method for each object, a common initialize method performs the same operation.

var initialize = function() {
  var result = this.critiques.reduce(function(prev, current, idx, arr) {
    return prev['stars'] + current['stars'];
  });
  this.critiquesAvg = result / this.critiques.length;
  return this;
};

var dealers = [({
  "id": 1874,
  "critiquesAvg": 0,
  "critiques": [{
    'author': 'John Does',
    'comment': "I like it",
    'stars': 5
  }, {
    'author': 'Jacob Works',
    'comment': "I like it too",
    'stars': 4.5
  }],
  init: initialize
}).init(), ({
  "id": 1345,
  "critiquesAvg": 0,
  "critiques": [{
    'author': 'John Does',
    'comment': "I like it",
    'stars': 5
  }, {
    'author': 'Jacob Works',
    'comment': "I like it too",
    'stars': 5
  }],
  init: initialize
}).init()];

DEMO

Answer 7

Answer №4

It was Robby who initially did it, but I decided to turn it into a function

function processData(data){
    //to avoid global data overwrite as objects are references
    var newData = data;
    var total = newData.critiques.reduce(function(x, y) {
        return x.stars + y.stars 
    });
    var averageRating = total / newData.critiques.length;

    newData.critiquesAvg = averageRating;
    return newData;
}

var initialData = { 
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
};

initialData.critiques.push({
    'author': 'Wacob Works',
    'comment': "I like it too",
    'stars' : 3.5
});

initialData = processData(initialData);

Great! The update aligns with your needs, hope this solution helps http://jsbin.com/sevor/1/edit

var dealers = [{
  "id": 1874,
    "critiquesAvg": 0 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
},
{
    "id": 1345,
    "critiquesAvg": 5 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 5
        }
    ]
}
];

var Dealers = {
    calculateAverage: function(dealer){
        var sum = dealer.critiques.reduce(function(x, y) {
            return x.stars + y.stars; 
        });
        var average = sum / dealer.critiques.length;
        return average;
    },
    generateAverages: function(allDealers){
        for(i=0;i<dealers.length;i++){
            dealers[i].critiquesAvg = this.calculateAverage(dealers[i]);
        }

        return allDealers;
    }
};

dealers = Dealers.generateAverages(dealers);

dealers.push({
    "id": 1346,
    "critiquesAvg": 0 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 5
        }
    ]
});

dealers = Dealers.generateAverages(dealers);
console.log(dealers);

Answer 8

It was Robby who initially did it, but I decided to turn it into a function

function processData(data){
    //to avoid global data overwrite as objects are references
    var newData = data;
    var total = newData.critiques.reduce(function(x, y) {
        return x.stars + y.stars 
    });
    var averageRating = total / newData.critiques.length;

    newData.critiquesAvg = averageRating;
    return newData;
}

var initialData = { 
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
};

initialData.critiques.push({
    'author': 'Wacob Works',
    'comment': "I like it too",
    'stars' : 3.5
});

initialData = processData(initialData);

Great! The update aligns with your needs, hope this solution helps http://jsbin.com/sevor/1/edit

var dealers = [{
  "id": 1874,
    "critiquesAvg": 0 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 4.5
        }
    ]
},
{
    "id": 1345,
    "critiquesAvg": 5 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 5
        }
    ]
}
];

var Dealers = {
    calculateAverage: function(dealer){
        var sum = dealer.critiques.reduce(function(x, y) {
            return x.stars + y.stars; 
        });
        var average = sum / dealer.critiques.length;
        return average;
    },
    generateAverages: function(allDealers){
        for(i=0;i<dealers.length;i++){
            dealers[i].critiquesAvg = this.calculateAverage(dealers[i]);
        }

        return allDealers;
    }
};

dealers = Dealers.generateAverages(dealers);

dealers.push({
    "id": 1346,
    "critiquesAvg": 0 ,
    "critiques":[
        {
            'author': 'John Does',
            'comment': "I like it",
            'stars' : 5
        },
        {
            'author': 'Jacob Works',
            'comment': "I like it too",
            'stars' : 5
        }
    ]
});

dealers = Dealers.generateAverages(dealers);
console.log(dealers);

Creating a JSON property value in real-time

Answer №1

Answer №2

Answer №3

Answer №4

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