CODEWITHSUNDEEP
javascriptobject
user3216499
user3216499

Reputation: 45

javascript getter on private variables

I'm trying to create a getter on the following:

function Field(val){
    this.value = {};
}

Field.prototype = {
    get value(){
        return this._value;
    },
    set value(val){
        this._value = val;
    }
};

But what I was able to achieve is a getter for field.value

I want to achieve something like this:

field.value.foo['20'] = 'some_value'; // ==> Setter
field.value.foo['20']; // 'some_value' ==> Getter

But I was not able to achieve this, using the above code .. Can someone help ..

Upvotes: 0

Views: 67

Answers (2)

r8k
r8k

Reputation: 88

You can actually solve this in ES5. I'm documenting this here, for other users to help gain from it..

function Foo() {
    this.__value__ = {};
    this.__value__['20'] = 'some_value';
};

Foo.prototype.__defineGetter__('foo', function() {
    return this.__value__;
});

function Field() {
    this.__value__ = new Foo();
};

Field.prototype.__defineGetter__('value', function() {
    return this.__value__;
});

Now, to test this ..

var field = new Field();
var value = field.value.foo['20'];
console.log(value);

I've updated a JSFiddle here

Upvotes: 0

Denys Séguret
Denys Séguret

Reputation: 382168

What you want is a generic getter/setter, able to change any property of your value object.

Unfortunately, this isn't possible with the current version of ECMAScript, you'll have to wait for proxies which should be available with ECMAScript 6 (and are available in the last gecko).

See ES6 wiki for direct proxies.

In the meanwhile, there's probably a solution with the current state of JavaScript for your real problem.

Upvotes: 1

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