Manage errors and translations in nodejs - node.js

Question

My nodejs application uses a basic REST communication style to allow an HTML web ui to pass commands.
For instance:
http://address/api/config/cmd1
http://address/api/config/cmd2
http://address/api/network/cmd3
...
In return, my web ui gets a JSON result of the form:
{
"success": true
}
or
{
"success": false,
"errorMsg": "Wrong parameter blabla"
}
My problem is, I now need to translate error messages on client-side (in many languages), and the english "errorMsg" is too variadic and too long to be a translation key.
So I need something like an "errorCode" (an integer, probably) and I'm searching for a strategy into my nodejs application to manage error codes. I don't really know what is usually done for that, considering I usually use throw new Error("message") to return the message directly to the web ui.
I don't know if it's better to make a list of uniq error codes for all my REST API of a contextual error list for every subset of this API.
UPDATE: finally, I opted for a string error id. For instance, "wrong argument for this command" becomes "WrongArgument" and will be used to identify the error on GUI side and thus, perform the localization process. And finally, I don't need to make the error id uniq.

Answer 1

Using a custom Error class in the back-end with error identifier will allow the front-end to directly use its translation module, without modifications.
From your Server, one can process the standard error by creating a custom class, throw the class, catch it in your controller and send to the front-end the response with correct http status and error id.
The reasons are:
1 - Front-end code maintanability.
2 - Keeping errors systems data on back-end logs because they might be sensitive. It should not be return to the client side.
I agree with naming identifier code instead of using a code number. This because it s hard to pre-define a range for each error type (SQL, API, Authentication...). And it s harder when the error may be found in different service.
Scope: In the front-end service, i define a scope when calling the server, so that if there is need for a global error to be more specific, it is there. The scope is just a string with the name of the page where the ressources is used, also found in JSON lang files.
If 'ld like to check this code out and give comments, it will be great:
'https://codepen.io/Aymer-El/pen/OJoRVgZ'
Also leaving place for a debug message in the response may help front-end devs. Tho, this is optional.