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Here, i am implementing an GeoMap asset which has all the countries. in this, all countries has their own class such as BTNMongolia, BTNHungary etc. i have only countries name to get object and based on countries name, i want to get object of the country's class. i'm doing like this.

function countryObject(country) {
    switch (country) {
        case 'mongolia':
            return new BTNMongolia();
        case 'mongolia':
            return new BTNHungary();
        case 'mongolia':
            return new BTNComoros();
        case 'mongolia':
            return new BTNAntiguaandBarbuda();
        case 'mongolia':
            return new BTNSouthKorea();
        case 'mongolia':
            return new BTNAustralia();
        case 'mongolia':
            return new BTNTajikistan();
        default:
            return null;
    }
}

here, to get object, i want to get object of the country'class from the country'name itself. is there is a short way to do that?.

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3
  • 5
    amazing each case is same, what really do you want??? Commented Aug 8, 2014 at 11:44
  • it's result of copy paste. Commented Aug 8, 2014 at 11:44
  • 1
    possible duplicate of Get object class from string name in javascript Commented Aug 8, 2014 at 11:56

4 Answers 4

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The main idea as below, you will need to check whether it exist to return null :

return new window["BTN" + country.capitalize()]();

If your class under a namespace, you may do it this way:

return new myspaces["BTN" + country.capitalize()]();

As for string capitalize you can refer this post.

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1 Comment

Be warned, this doesn't work if your constructors are in a namespace other than window
2

This could be a solution. You can use a dictionary like bellow.

function countryObject(country){
    var countryObject = {
        mongolia:  BTNMongolia,
        hungary:   BTNHungary,
        comoros:   BTNComoros,
        australia: BTNAustralia
        // ...
    };
    return new countryObject[country]();
}

I've not specified the full code. So please extend it.

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4 Comments

You don't need to instantiate every one each time the factory function is called - just reference the constructors and return new countryObject[country];
that doesnt really answer his question, its exactly the same as switch-case logic, he still needs to map everything while he asks how to do it blind without mapping...
@Emissary thanx for the catch, updated my answer now it won't create every time.
@Emissary ohhh I got it, What I was thinking they both are same, but when you used the terms then I realized, many many thanx.
0

I believe this questions was already answered here Get object class from string name in javascript. Basically don't use eval, store the list of classes in a map and then look them up in the map.

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-2

You could try something like return eval('new BTN'+country+'()'). That doesn't seem like a good use of eval, but I can't think of another way of doing it without explicitly listing all the possible classes.

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