Javascript recursive json decleration (es6)

Question

I'm trying to figure out how I can organize my variables, and this is the outcome I want:

settings.txt.token => 'txt'
settings.txt.path => '/txt/'

This is obviously a very simple example, but I want settings.txt.path to depend on settings.txt.token. So a sudo decleration would be:

export var txt = {
   token: 'txt',
   path: '/' + token + '/'
};

Is there a good way to do this? Note that I'm using ES6.

This is not JSON, this is only JavaScript. – zero298 Mar 09 '16 at 23:11 — zero298, Mar 09 '16 at 23:11

jfriend00 · Accepted Answer · 2016-03-09T23:08:20.577

A static declaration of one property cannot refer directly to another property in the same object because the object itself is in the process of formation and does not fully exist yet and javascript does not have syntax for referencing sibling properties from a static declaration. So, you have to postpone the calculation of the value for the new property until after the object exists. You can do that a couple of ways.

One is with a getter:

export var txt = {
   token: 'txt',
   get path() { return '/' + this.token + '/';}
};

The other is to just add the property to the object after the static declaration has completed:

export var txt = {
   token: 'txt',
};
txt.path = '/' + txt.token + '/';

The getter option has the advantage that if .token is modified, subsequent requests for .path will automatically reflect the new value of .token. The second option is not dynamically linked. The txt.path value will not automatically change if txt.token is changed. You can select either behavior.

Maybe he just wants this as the initial value of `path`, not keep them always linked, so the getter may not be appropriate. — Barmar, Mar 09 '16 at 23:02
@Barmar - Maybe, maybe not - not sure. I offered both options. — jfriend00, Mar 09 '16 at 23:07

score 0 · Answer 2 · answered Mar 09 '16 at 22:48

0

Yeah, you can't reference fields in object initializer. But you can in constructor:

export var txt = new function(){
    this.token = "txt";
    this.path = "/" + this.token + "/";
}

answered Mar 09 '16 at 22:48

weaknespase

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Javascript recursive json decleration (es6)

2 Answers2