Nodejs "Unexpected token ." when creating object

Question

I have tried to search my problem but I couldn't even know how to ask it. I looked similar questions but I couldn't find anything. So here is my problem.

I have two js files. First one is constant.js which keeps HTTP field names. Here is the code snippet of it

module.exports = {
    USERNAME: 'username'
};

The second file is test.js and I would like to create some object inside of this file. While creating an object I would like to use constant.js file property names as shown in below:

var constant = require('./constant');

var x = {
    constant.USERNAME: "test"
};

console.log(x);

When i execute test.js I expected to see { username: 'test' } in the console but I got this following error:

constant.USERNAME: "test"
        ^
SyntaxError: Unexpected token .
    at exports.runInThisContext (vm.js:73:16)
    at Module._compile (module.js:443:25)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:501:10)
    at startup (node.js:129:16)
    at node.js:814:3

I don't know why is it happening. Why can't I create my object? Any help would be greatly appreciated.

NOTE: Both files are on the same folder. There is no module export error. When I try to console.log(constant) it works well.

Jozef Chocholacek · Accepted Answer · 2016-07-14 06:43:07Z

3

JS object literals (x = { ... }) consist of name: value pairs, where the name is a literal (and JS does not allow . in it), and you cannot use another variable here. To achieve what I think you want to achieve, I would do:

x = {};
x[constant.USERNAME] = "test";

answered Jul 14, 2016 at 6:43

Jozef Chocholacek

2,9242 gold badges22 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ROAL · Accepted Answer · 2016-07-14 06:42:51Z

3

In case of literal object notation, the property names are not evaluated. Furthermore, constant.USERNAME is an invalid property name.

If you want to use the value of constant.USERNAME as the property name, you need to use the "array notation", like this:

var x = {};
x[constant.USERNAME] = 'test';

answered Jul 14, 2016 at 6:42

ROAL

1,7891 gold badge14 silver badges21 bronze badges

Comments

Alexey Ten · Accepted Answer · 2016-07-14 06:52:35Z

2

You should either use new syntax from ECMAScript 2015 (supported in nodejs 4 and newer):

var x = {
    [constant.USERNAME]: "test"
};

or stick with plain old:

var x = {};
x[constant.USERNAME] = "test";

edited Jul 14, 2016 at 6:52

answered Jul 14, 2016 at 6:44

Alexey Ten

14.5k6 gold badges49 silver badges62 bronze badges

Collectives™ on Stack Overflow

Nodejs "Unexpected token ." when creating object

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related