JavaScript: Declare variable inside object declaration

Question

Is it possible to declare variables in JavaScript inside an object declaration? I'm looking for something similar to

var myObject = {
    myLabel: (var myVariable)
};

instead of having to write

var myVariable;
var myObject = {
    myLabel: myVariable
};

EDIT

I want this in the context of Node.JS. This is what I have:

var server = {};
var database = {};
var moar = {};

module.exports = {
    server: server,
    database: databse,
    moar: moar
};

doStuffAsync(function callback() {
    // Populate variables
    server = stuff();
    database = stuff2();
});

myObject.myLabel would be undefined anyway, just like myObject.yourLabel, so what's the point? — danronmoon
– danronmoon, Commented Jan 15, 2013 at 14:15
why don't you pass module.exports to your doStuffAsync function so that you can set server and database directly at that object? — t.niese
– t.niese, Commented Jan 15, 2013 at 14:22
The only reason I can think of doing this is to save one line of code. If you're worried about the number of lines of code, look into minification instead of destroying your readability. — jbabey
– jbabey, Commented Jan 15, 2013 at 14:26

palerdot · Accepted Answer · 2015-07-12 15:39:35Z

9

If you want to scope a variable inside an object you can use IIFE (immediately invoked function expressions)

var myObject = {
    a_variable_proxy : (function(){ 
        var myvariable = 'hello'; 
        return myvariable; 
    })()
};

edited Jul 12, 2015 at 15:39

answered Jan 15, 2013 at 14:15

palerdot

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4 Comments

t.niese Over a year ago

sould be a_variable_proxy : (function(){ var myvariable; return myvariable })() otherwise it is a syntax error

codingbiz Over a year ago

Need to remove the semi-colon :)

bfavaretto Over a year ago

Maybe that's what the OP is looking for. But technically the variable is not scoped to the object as you said, it's scoped to the IIFE.

Nimeshka Srimal Over a year ago

@bfavaretto but since it returns the variable, it can be accessed within the class. (new reply to an old comment, but hope it will help a new comer.)

Jan Hančič · Accepted Answer · 2013-01-15 14:14:12Z

3

You can assign a value to a key directly.

If you now have:

var myVariable = 'some value';
var myObject = {
    myLabel: myVariable
};

you can replace it with:

var myObject = {
    myLabel: 'some value'
};

answered Jan 15, 2013 at 14:14

Jan Hančič

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1 Comment

Jonathan J. Pecany Over a year ago

That is something he/she was trying to avoid.

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