Creating objects with variable properties

Question

I'm trying to do this:

var sortAfter = req.query.sortAfter || '_id';
var ascending = req.query.direction || -1;
var sorted = {sortAfter: ascending};

But a console.log(sorted) output the following object:

{ sortAfter: -1 }

It's like the first variable is not used in the object creation...

Question: How do i get the object to be made of two variables, and not one variable and one fixed string?

possible duplicate of Passing in dynamic key:value pairs to an object literal? — Felix Kling
– Felix Kling, Commented Oct 23, 2013 at 8:22

Lifecube · Accepted Answer · 2013-10-23 08:24:10Z

2

try this way:

var sortAfter = req.query.sortAfter || '_id';
var ascending = req.query.direction || -1;
var sorted = {};
sorted[sortAfter] = ascending;

answered Oct 23, 2013 at 8:24

Lifecube

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Comments

deceze · Accepted Answer · 2013-10-23 08:21:46Z

1

In object literals, the keys are always literals, they're never variables. If you want to set a dynamic object key, you'll have to do it like this:

var sorted = {};
sorted[sortAfter] = ascending;

answered Oct 23, 2013 at 8:21

deceze♦

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c.P.u1 · Accepted Answer · 2013-10-23 08:21:51Z

1

Use the subscript/bracket notation:

var sorted = {};
sorted[sortAfter] = ascending;

The subscript operator will convert its operand to a string,

answered Oct 23, 2013 at 8:21

c.P.u1

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