How to use the value of a variable as a property of an object?

Question

In the example below, the object doesn't seem to understand which category is a variable and so it uses as a string:

var categoria = "Carros";
var obj       = {
    categorias: {}
};
obj.categorias = {...obj.categorias, categoria: {}}
console.log(obj.categorias)

I want the category property to be named "Cars" and not category. I tried it the way below, but it returns a template string error:

var categoria = "Carros";
var obj       = {
    categorias: {}
};
obj.categorias = {...obj.categorias, `${categoria}`: {}}

https://stackoverflow.com/questions/695050/add-a-property-to-a-javascript-object-using-a-variable-as-the-name — epascarello, Oct 07 '21 at 16:29
Does this answer your question? [Add a property to a JavaScript object using a variable as the name?](https://stackoverflow.com/questions/695050/add-a-property-to-a-javascript-object-using-a-variable-as-the-name) — Robin Zigmond, Oct 07 '21 at 16:31

score 5 · Accepted Answer · answered Oct 07 '21 at 16:26

5

Use square brackets!

const categoria = "Carros";

const obj = {
  categorias: {}
};

obj.categorias = { ...obj.categorias, [categoria]: {} };

console.log(obj.categorias);

answered Oct 07 '21 at 16:26

MikeM

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Perfect! I didn't know about this feature. Thank you very much. – Otavio Fagundes Oct 07 '21 at 16:30
You're welcome. It's a [computed property name](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer#computed_property_names)". – MikeM Oct 07 '21 at 16:31

How to use the value of a variable as a property of an object?

1 Answers1