How do you dynamically name and create an object in javascript?

Question

normally to create an object you would write:

function Dog(name) {  
  this.name = name;  
}  

fifi = new Dog("fifi");

How do I dynamically name the object so that I can write:

var name = "fifi";  
[name] = new Dog(name);

to achieve the same outcome as:

fifi = new Dog("fifi");

Nick Craver · Accepted Answer · 2010-12-25 11:20:51Z

3

If you know the object you're creating the variable on (a property, not just a variable) you can use bracket notation, like this:

var dogs = {};
dogs[name] = new Dog(name);

Later you could access it either way:

dogs.fifi
//or...
dogs["fifi"]

If it's a global variable you're after, that object (instead of dogs above) would just be window.

answered Dec 25, 2010 at 11:20

Nick Craver

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1 Comment

Anthony H Over a year ago

Thanks for the help, Nick. In essence, we are creating a hash with dynamically named keys and values. genius.

Felix Kling · Accepted Answer · 2010-12-25 11:22:35Z

3

This would do it:

function createDog(name, scope) {
    scope[name] = new Dog(name);
}

Then you could do:

createDog('fifi', window);

or pass any other object as your scope.

But I would not tie objects and variables to close together. One advantage of objects is that you can pass them freely around and several variables can have a reference to the same object.
I would give it a more meaningful name, that describes the purpose of that object.

answered Dec 25, 2010 at 11:22

Felix Kling

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