Transform the object into JSON while excluding specific (private) attributes

Question

Transform the object into JSON while excluding specific (private) attributes

I recently started using dean edwards base.js for organizing my program into objects. I must say, base.js is truly amazing! But now I have a question that doesn't require prior knowledge of base.js to answer.

Within one of my objects, I have a property called ref which holds a reference to a DOM element. This object needs to be serialized as JSON using JSON.stringify, but the presence of circular structures within DOM elements makes it impossible to convert the object to JSON.

To overcome this issue, I have implemented a method called html() to return the ref property. However, I need ref to be a private property accessible only within the object, ensuring it is not included in the JSON serialization process by stringify.

Can anyone suggest the best approach to achieve this?

javascript json

Answer 1

Answer №1

JavaScript does not allow private properties, but there is a clever workaround.

If you use JSON.stringify on an object that has a method called toJSON, the method will be automatically called to create a JSON representation of the object. This means you can implement this method yourself to customize the output.

One approach is to create a shallow copy of the object with only the desired properties:

MyConstructor.prototype.toJSON = function() {
    var copy = {},
        exclude = {ref: 1};
    for (var prop in this) {
        if (!exclude[prop]) {
            copy[prop] = this[prop];
        }
    }
    return copy;
};

See DEMO

Alternatively, you could also use a custom replacer function, but it may be more challenging to selectively exclude certain properties like ref:

JSON.stringify(someInstance, function(key, value) {
     if(key !== 'ref') {
         return value;
     }
});

Another DEMO

Answer 2

JavaScript does not allow private properties, but there is a clever workaround.

If you use JSON.stringify on an object that has a method called toJSON, the method will be automatically called to create a JSON representation of the object. This means you can implement this method yourself to customize the output.

One approach is to create a shallow copy of the object with only the desired properties:

MyConstructor.prototype.toJSON = function() {
    var copy = {},
        exclude = {ref: 1};
    for (var prop in this) {
        if (!exclude[prop]) {
            copy[prop] = this[prop];
        }
    }
    return copy;
};

See DEMO

Alternatively, you could also use a custom replacer function, but it may be more challenging to selectively exclude certain properties like ref:

JSON.stringify(someInstance, function(key, value) {
     if(key !== 'ref') {
         return value;
     }
});

Another DEMO

Answer 3

Answer №2

Check out this example of how to control variable visibility:

function Sample(){
       this.var1 = 'public property'; // This property is accessible from outside the object

       var var2 = 'private property'; // This property is private.

       var self = this;

        this.showVar = function(){
            alert(var2);
            alert(self.var1);
        };
    }

var sampleObj = new Sample();
sampleObj.showVar();

Answer 4

Check out this example of how to control variable visibility:

function Sample(){
       this.var1 = 'public property'; // This property is accessible from outside the object

       var var2 = 'private property'; // This property is private.

       var self = this;

        this.showVar = function(){
            alert(var2);
            alert(self.var1);
        };
    }

var sampleObj = new Sample();
sampleObj.showVar();

Transform the object into JSON while excluding specific (private) attributes

Answer №1

Answer №2

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